The most important change concerns the words "President" and "God" -- according to the new rules both words must be capitalized if they refer to the President of the Republic of Belarus and the supreme being of monotheistic religions (not to be confused). Other presidents and gods unfortunately don't share this privilege. (Although already under Belarusian law there is no president except the President and it is forbidden to use the title in any other cases).
The new legislation also establishes an official spelling standard, which may deliver a blow to the alternative spelling standard called"Tarashkevitsa" which is used by some independent publications in Belarus and abroad (including RFE/RL's Belarus Service).
-- Siarhej Shupa