hotmail, following the footsteps of gmail are using ajax to run their service
I received an email telling me that being a "VIP" hotmail member, I am invited to use their service - dunno what made me a VIP - maybe they are aware that we have many status-conscious people in Pakistan - yes, I am in Pakistan, only I set my location to USA to try one of those tricks for increasing mailbox storage
The service is nice and slick with an outlook like interface drag/drop for moving messages to folders and right-click context menus
In a clear "inspiration" from gmail, they have added auto-complete in the mailto address bar, their news about this feature is well worth a read:
"Start typing a name and—pow!—up pops a list of possible recipients from your contact list. Click on the one you want and you're done."
It's the "pow!" that converted me.... (sarcasm)