AT&T won't support it as of yet, although it is being looked into as a possible future item due to the fact if you are logged into MSN on a PC all your MSN/Hotmail emails cease to send to your device...the only fix for it is to install the RIM approved MSN client on your Berry.
I have the service books and managed to get it installed on my phone, but like the rest error 65! I am with suncom which is supposed to switch to tmobile this september. Anybody figured out how to get it to work? I use webmessenger but only for my live account. Figured this would be easier. The only way I could install on my phone was to delete the vender info in the cod file for live messenger. It installed without a hitch, but when I go to log in that stupid error 65. Any help would be appreciated.