According to a post from Steven Abrahams, the Lead Program Manager on the Windows Live team, several of the Windows Live Essentials 2011 programs received updates today.

This minor release includes numerous updates across all of the programs in the Essential package, including Windows Live Messenger, Mail, Photo Gallery, Movie Maker, Family Safety, Writer, and Mesh. In the coming weeks, customers on Windows Vista SP2 and Windows 7 will receive a notification prompting them to upgrade to the new version. Since this release contains critical fixes for the Essentials package, in a few months, the update will become required for all eligible customers.

The mandatory update for all customers in a few months means that anyone who may still be using Windows Live Essentials 2009 will have to upgrade to the 2011 version of the programs.  That upgrade should be fairly seamless but will expose a lot of new features to 2009 users.

You do not have to wait for the prompt to update to this new release.  You can already download all of the programs at the Windows Live Essentials website.