Just noticed that Microsoft CRM Online is now officially available. Not sure how personally invested I'll get in learning it. I responded to several Beta trial invitations, but never received an invite (and we're a Microsoft partner?!?).
There is a 30 day trial that you can apply for.
Kudos to Microsoft for changing the name from "Live" CRM to simply "CRM Online" (As Simon Cowell might say "The whole Live brand just seems a bit too cabaret-ish for business software applications" ).