Through my somewhat extensive coverage of the Outlook.com story, Microsoft has announced that it is now out of preview a few days ago. Outlook.com is now a full blown service, and is ready to take in millions users.
The reason why I said that it is ready to take million of users is because during the entire preview stage Microsoft was adding infrastructure upgrade to keep up with the demand of Outlook.com, which was more than expected according to them.
If you upgraded from Hotmail, Outlook.com is actually ran on separate servers, but you still have all of your email, contacts, etc. If you do a WHOIS on Outlook.com you can see that the MX records for the domain use the exact ones from Hotmail, so basically the back end is just about the same, but what will change is the front end, which includes the interface.
Must earlier than expected, is Microsoft announcing that they will start moving over existing Hotmail users starting this summer, which is a lot earlier than the time period given last time. However, Hotmail users will be sent plenty of emails and will be hit with target advertisement asking them to upgrade to Outlook.com on their own before hand, before being forced over if they choose to not upgrade on their own.
Another change that has been added is that once you upgrade to Outlook.com, you can't switch back. That's right -- once you switch over there is no turning back, which you could do when Outlook.com was in preview.
The only service left without an upgrade so far is Hotmail Calendar, which still uses the "old" Windows Live theming. An update is said to come out "soon", but that's what they've said months ago. I'm personally hoping the update comes out soon, as the metro styled Microsoft services just don't fit with the old Windows Live themes.