Roughly about 3 weeks ago or so I was fortunate to receive an invite for the new hotmail code name Kahuna. The official name is far less exciting, Windows Live Mail (http://mail.live.com ).
So far I think it’s awesome! While I realize it is still in beta, it seems very stable. I have yet to experience any performance bottle necks.
The obvious question of course is “how does it compare with Gmail (http://gmail.com )?”. I think the answer will vary, but personally I am so used to Outlook. After all I have been using the program since 97, same version as the year. And so the familiar interface gives the edge to Live Mail. All in all, I have to commend the MSN team behind this awesome program.
Frankly I couldn’t imagine going back to the old hotmail.
I googled, well 1 out of 2 is not bad 
, some to find some links on how Microsoft developed Live Mail. See below:
http://www.shahine.com/omar/MailBeta.aspx
http://www.shahine.com/omar/TheOriginsOfKahunaTheCodename.aspx
http://www.betanews.com/article/Microsoft_Testing_New_Hotmail_Interface/1121099209