As always, it was just a matter of time till someone worked out how to register @live.com and other geographic accounts like @live.co.uk for the newly branded Microsoft services (including email).
It looks like Mess were the first to publish how: mess.be
I registered a couple, but am getting an error message now:
We are working to fix a temporary problem with our sign-up service. Please try again.
Error code: 32 Error code32:0×00000000::Sun, 12 Nov 2006 17:37:33 UTC
Update:
Yep, Microsoft have patched the hole http://bink.nu/Article8814.bink - thats a shame as I had a couple more addresses in mind!