GigaOM provides some details from UBS Investment Research from the latest AT&T investor meeting.
From it, we find that AT&T is going to be using the iPhone launch as a "branding event and increase its advertising around the product to cement the AT&T Mobility name in the market." Apple, of course, is expected to be marketing the iPhone aggressively as well.
The report also reinforces what was previously hinted at -- that the iPhone does not appear to be subsidized by AT&T. This means that AT&T may actually make a small profit margin on the sales of the iPhone.
This benefit, however, may be outweighed by the monthly revenue sharing that Apple reportedly insisted on. Exact amounts are not available, but a portion of the AT&T monthly subscription plan for the iPhone is reportedly going back to Apple. Depending on how much that portion is, AT&T could even see a decline in monthly revenue for each existing customer that switches to the iPhone.
Details are scarce, of course, and the article states that "revenue share might be different for new customers vs upgraded subscribers". Regardless, AT&T is certainly banking on attracting new customers with the iPhone launch.