The move confounded conventional wisdom that Putin was about to name First Deputy Prime Minister Sergei Ivanov as prime minister and, by extension, as his chosen successor as president.
But after accepting the resignation of Prime Minister Mikhail Fradkov, Putin left Moscow for a trip to the Volga region without naming a replacement.
State Duma Speaker Boris Gryzlov then shocked the Russian political elite by announcing that Putin had nominated Viktor Zubkov, the 65-year-old head of the Federal Financial Monitoring Service, as his new prime minister.
Political analysts were confounded by the move. Maria Matskevich, of the Russian Academy of Sciences' Institute of Sociology, says there is no easy explanation for what Putin was thinking.
"Only insiders who really know what is going on can answer that question," she says. "External commentators cannot explain this. And the insiders will either not give an answer or they will put out some disinformation like they did earlier."
Indeed, shortly after Fradkov's resignation -- but before Zubkov's nomination was announced -- political analysts of every stripe indicated that Ivanov would be named prime minister.
Sergei Markov, who heads the Institute for Political Studies and has close Kremlin ties, said the new prime minister would likely be a "political appointment." Markov said that Ivanov was "candidate number one" and First Deputy Prime Minister Dmitry Medvedev was "candidate number two."
The "Vedomosti" daily reported in today's edition that Ivanov would replace Fradkov very soon.
Even Fradkov and Putin added to the impression that a presidential successor would be apparent in the appointment of a new prime minister. Meeting in the Kremlin, Fradkov said he was resigning due to "approaching significant political events in the country" and his own desire "to give Russia's president full freedom of decision, including staff decisions."
Russia is scheduled to hold parliamentary elections in December and a presidential election in March.
And Putin indicated that the changes in the government were related to the elections.
"Perhaps we should all think together how to build a structure of power and governance that better corresponds to the pre-election period and prepares the country for the period after the parliamentary elections and the March 2008 presidential election," Putin said.
Matskevich says that today's developments could be a signal that when it comes to figuring out who will succeed Putin in the Kremlin -- or even if Putin will leave the Kremlin when his term expires next year -- all bets are off.
"It is completely possible that this is a signal that all that we thought was completely certain in terms of how things will develop is mistaken. It is a signal that there is no certainty about how things will develop in Russia," Matskevich says.
Many Kremlin watchers say today's surprise move is a sign that Putin and his inner circle have not settled on a successor.
Some analysts have also suggested that Zubkov could be part of the so-called "technical president" scenario, in which Putin turns the presidency over to a weak figure temporarily -- and then returns to the Kremlin after a brief hiatus.
The Russian Constitution forbids the president from serving more than two consecutive terms -- but does not forbid Putin from returning to office after another president has been in power.
Paul Quinn-Judge, a Russia analyst and former Moscow correspondent for "Time" magazine, offers a different view: that today's move may be an indication Putin may be panicking as the time approaches for him to hand over the keys to the Kremlin.
"The fact that Putin comes up with something unexpected is not necessarily a sign of great cunning and political acumen. It could well be a sign that the man is as anxious and indecisive and perhaps even panicky as some analysts -- myself included -- would suspect," Quinn-Judge says.
Quinn-Judge adds that Putin's reputation as a skilled political operator pulling all the strings is greatly exaggerated. And as his second term draws to a close, the Russian president could be becoming increasingly isolated and more prone to irrational decisions.
"Bottom line, there is only one thing we're sure of: Putin wants to keep control. Whether he keeps control as president or behind the scenes as the puppet master, we don't know. I think he is honest enough about himself to realize that he is not that good as a puppet master. Some people might say he is more a puppet than a puppet master," Quinn-Judge says.
Putin has said repeatedly that he will not attempt to change the Russian Constitution and seek a third term. But many of his closest political allies -- most notably Federation Council Speaker Sergei Mironov -- have continuously suggested that he remain in office.
Quinn-Judge says that despite Putin's strenuous protestations to the contrary, he may indeed be planning to remain in the Kremlin.
"I look with interest at the way that he has not told people who are abjectly obedient to him not to mention third terms," he says. "This leads me to believe that he doesn't want to squash the whole subject until he has decided one way or the other. And one would have to assume that he hasn't decided one way or the other."
But for now, Russia will almost certainly have Zubkov as prime minister.
Zubkov ran state farms in the Leningrad Oblast. In the 1990s he worked in the St. Petersburg city government when Putin was deputy mayor.
The State Duma is scheduled to vote on Zubkov's confirmation on September 14, one day before his 66th birthday.
For Ivanov, the man who might have been prime minister, the announcement appeared to be business as usual.
"Governments resign sooner or later in any democratic country," he said.
"I think what [Putin's] doing is he's clearing out the government of all potentially independent minded ministers and putting in place a guy who's extremely loyal to him and who also has a lot of dirt on everyone else." -- Michael McFaul of Washington's Carnegie Endowment and Stanford's Hoover Institution.
"It is completely possible that this is a signal that all that we thought was completely certain in terms of how things will develop is mistaken. It is a signal that there is no certainty about how things will develop in Russia." -- Maria Matskevich of the Russian Academy of Sciences' Institute of Sociology.
"We are probably looking at a government that will be transitional and which will be handed over to a successor who will be named later." -- Andrei Ryabov, a political analyst at the Moscow Carnegie Center.
"The fact that Putin comes up with something unexpected is not necessarily a sign of great cunning and political acumen. It could well be a sign that the man is as anxious and indecisive and perhaps even panicky as some analysts -- myself included -- would suspect." -- Paul Quinn-Judge, a Russia analyst and former Moscow correspondent for "Time" magazine.
"Who will be his successor? That's for Putin to decide. It could be [First Deputy Prime Minister] Sergei Ivanov, it could be [First Deputy Prime Minister] Dmitry Medvedev, it could even be the head of Russia's railways [Vladimir] Yakunin. But I think that whoever it is, this is a signal that the president is making his choice." -- Yevgeny Volk, the director of the Heritage Foundation.