Is AT&T in Cahoots with Text Messaging Spammers?

Sorry for not posting the past two weeks but I was away for work and then took a short family vacation.

Since switching to the iPhone 3G last month, I've noticed an huge increase in text message spam. Before on my Samsung Blackjack I only received a few text spam per month but now with the iPhone 3G I'm getting at least 4-5 per day!

Given I was an AT&T customer with the same mobile number and a bundled Medianet data/text plan prior to the iPhone 3G, I can only surmise that AT&T somehow notified text spammers when I switched to their 3G data plan and added on 200 text messages for $5 a month.

Anyone else experiencing this?