Did you know that a giant company can have a corporate hobby? AT&T Wireless' hobby is messing around with iPhone related phone plans. AT&T provided a combined voice plus data plus text messaging as well as a pre-paid voice plus data plan when the first iPhone was released in 2007. When the iPhone 3G was released last summer, AT&T removed text messaging from the basic plan and provided a set of tiered text messaging plans ranging from $5 per month for 200 messages up to $20 per month for unlimited messages. So, what's changing this year with the release of iPhone OS 3.0 and the iPhone 3G S?

Macworld reports that MMS (Multimedia Messaging Service) will be included as a part of the existing SMS text messaging service...

AT&T: MMS 'no extra cost' for text bundle customers

However, as Macworld points out, AT&T could decide that MMS messages weigh more than a text message and may be counted differently.

Next, Erica Sadun notes over on TUAW that...

AT&T signals an abrupt end for prepaid iPhone plans

If you currently have a GoPhone plan for your iPhone, you definitely want to read the details of Erica's findings on this topic so far.

And, this brings us the big unknown AT&T iPhone plan change: How much will they charge for tethering and what will they deliver for this as yet unknown additional (optional) service fee? If it is more than $30 to $45 per month, I suspect many U.S. iPhone users will simply get a Verizon MiFi (3G WiFi router) for $60 per month to get faster 3G data service that AT&T currently offers.