I was browsing GDGT earlier today when I stumbled upon this interesting post. By what I can gather, after AT&T announced their data plan changes, this person started thoroughly checking their data usage. He noticed that his wife’s iPhone was making mysterious data transfers around 2:00 AM, and about 20 MB. This of course, should cause alarm to AT&T customers with 200 MB data plans.

It looks like others are chiming in claiming the same thing. Some are reporting that they called AT&T and that “they had no idea either.” Others say that 1:00 AM - 5:00 AM is when AT&T charges customers for data usage from earlier in the day. However, people in other countries report the same, 10 MB - 20 MB data transfers at the same time… MobileMe? Gmail? Perhaps, but 20 MB is an excessive amount of email/calendar/contact updates.

What it is exactly, I can’t find a consensus just yet. The iPhone was designed with unlimited in mind. Apparently some users are emailing Steve Jobs himself. Maybe we’ll learn more later.