MacBlogs is reporting that according to a source AT&T will charge US$30 per month for iPhone tethering and cap downloads at 5GB per month like they do for Blackberry users. AT&T will reportedly disable tethering if the 5GB bandwidth cap is exceeded. AT&T currently offers Blackberry tethering for an additional $30 per month over a US$30 per month for data (for a total of $60 per month).
They also say that you'll need to make the initial tethering connection through iTunes and that expected speeds are GPRS (30k), EDGE (110k), 3G (1000k). AT&T publicly announced the iPhone tethering plan on 06 November saying that it was coming “soon.”