The mainstream/free support for Windows Vista will officially end on April 10 2012 and will enter the “Extended Support” phase. This means no more new Vista service packs and newer Internet Explorer versions will be available for Windows Vista. Further more, no more new non security hot fixes will be released by Microsoft for Vista.
Check out the main differences between Mainstream and Extended Support phases here.
The complete support for Vista by Microsoft will officially end on 11 April 2017.