Windows Live Hotmail, currently in Milestone 10 of a unique and interesting beta, is set to come out of beta as early as this week, according to a number of indications, including this post on Messenger Stuff.  The post includes a screenshot of a French Hotmail email newsletter item, which says (translation from Messenger Stuff):

Just over few days before it's available to everyone!
The official launch of Windows Live Hotmail will take place in a few days! Therefore very little time remains for you to test before everyone has the new version...
The launch is nearly here!

In addition, our pal Darren Straight points to a Windows Live Hotmail Marketer Briefing being held at the Boston Sheraton this Tuesday (April 17).  While there's no mention of the end of the beta, clearly marketing for the final product is ramping up.

Our thanks to the Kahuna/Windows Live Mail/Windows Live Hotmail beta team for putting on a beta the way they're meant to be: open, inclusive, fun, and flexible.  No other beta has been as responsive to user requests, as open to feedback, or as willing to expose a work in progress in order to get the best out of beta testers, and out of Windows Live Hotmail. Congratulations!

Update: Windows Live Hotmail has started rolling out, with Belgium and India already upgraded.