A quick check of my new MobileMe email account, shows that I'm receiving email with xxxxxxx@me.com as the destination.
The smtp.me.com service doesn't seem to be working as of yet, so I just threw in the smtp.mac.com info and whammo, I'm emailing with my swanky new, yet slightly narcissistic, email address.
Since the email account hasn't officially launched, Apple could still take the account offline until the official launch.
Links:
[1] http://www.maclife.com/user/rbaldwin
[2] http://www.maclife.com/article/news/mobileme_email_address_live
[3] http://www.maclife.com/article/mobileme_goodbye_mac_hello_usefulness