I'm not sure about THIS specific problem but I do know that AT&T has been having problems with their SMS the past few days.
The AT&T forums have several people saying they're getting messages from phone numbers they don't even know, etc.
One guy said he got pictures from his girlfriend... but the phone number was NOT hers. He was NOT confusing it with the number that appears when the pic is sent from an email address.
Another person said they were receiving text messages from out of state people who were claiming that HIS/HER number had sent them a text message... yet his phone had no record of sending anything out.
Finally, one person had an issue where the to/from/subject was missing or all screwed up. This one sounds most like your problem.
Long story short... this "seems" to be an error and not a planned change.
My recommendation would be that you call AT&T and ask them about it before you go making any configuration changes on your end.