Now, I left MSN about a year and a half ago, just around the time that Cingular rebranded itself as AT&T. I'm hugely amused to see that MSN still has two entries for AT&T, neither of which are labeled as AT&T (Cingular mMode is Cingular; Cingular Media Net is AT&T Wireless).
Are they ever gonna fix that?
Bonus: It also doesn't work, likely because AT&T doesn't have a contract in place with Microsoft that would allow for Messenger-over-SMS functionality. Boo.