I can confirm that the following steps will allow Swirly to work on your AT&T iPhone.
First, you will need a regular AT&T/Cingular phone. I used a old LG CG325. It have also used a Samsung Blackjack as well. You should be able to use any phone as long as it is Media Net compatible.
Take the SIM from your iPhone, Insert it in to a standard phone, Make a phone call, wait about 5 minutes.
After 5 minutes go to the following link,
http://mymedianet.wireless.att.com/app/MC/Default.aspx
Enter in your mobile number(it might say your phone is not supported.. if so wait a little longer and try again), then at the next screen it will ask for a 4 digit code.
The 4 digit code will be sent to your phone via Text message.
Enter the code in on the website and then you should be able to access the main Media Net site.
Once you access the media net page.. select sports or something and drag it to the bottom of the website. Then click the picture of the phone on the right hand side to update the information.
It might send a text message to your phone with a link to go to. Go ahead and try to access the link.
It might give you a 403 forbidden error but that is okay.
Now take out the sim card and place it back in the iPhone.
Make sure the Swirly MMS Settings are as follows...
MMSC: mmsc.cingular.com
Proxy: 066.209.011.032
leave apn, username, and password fields blank..
Image Size: Maximum
UserAgent: Nokia_N95.
VIOLA!! Hope it works for you!