Six Apart announced a new official product lifecycle roadmap for Movable Type on Christmas, and the most important news in it seems to be that support for version 4.x will officially end December 31st, 2013. If you don't upgrade to MT 5.x by that time you are basically on your own... For most installations, upgrading from 4.x to 5.x shouldn't be a problem. But not all plugins are compatible between 4.x and 5.x, so there certainly is some work to be done for plugin developers who want their code to keep working on the latest MT. Should you need any help with your upgrade, feel free to contact me!
December 2012 Archives
Because I was at LeWeb in Paris for three days I missed the announcement, but Movable Type 5.2.2 is out (the first version using the new numbering scheme). The most important new features are the new 'Rainier' theme and an option to quickly add 'boilerplate text' to entries. The announcement & release notes are here.