At&t is apparently having a glitch in their system where their online account management system is showing pay-per-use charges for international SMS/data usage. From the reports I’ve read, it may be limited to the Chicago area, but it could be more widespread. I can vouch for this issue, being an At&t customer in the Chicago area, I noticed this in my usage on the website. You can check your account by doing *DATA# and Send and you’ll get a text message of your data usage.
On my account, its showing up under “GPRS PPU DOM WAP $0.01KB – WXP2OS”.
Here’s a thread at HowardForums. Here’s another one. Here’s a message in At&t’s forum, but you must be logged in to see this.