Features (From the Microsoft Connect website) :
* Sign-in and messaging in multiple locations - You asked for it, now you have it! You can now sign into Messenger from more than one computer at a time, up to four at once. Simply sign into Messenger from one computer, install Messenger on another computer and sign in using the same account. (Only works if all computers are running Messenger 9.0 Beta. Currently enabled only for users whose Windows Live ID country is US or Canada.)
* Signature sounds – Pick your own personal sound that your contacts will hear when you sign into Messenger (only works if you and your contacts have Me ... more