I agree with most of your post, but this doesn't make sense. AT&T is not in any way "blocking" this functionality. It is Apple's decision not to let third party apps run in the background. That is all Apple I am sure. AT&T is agreeing to do something extra to connect to and inform the Loopt apps on their own (assuming a person opts in, of course). I'm not sure why AT&T is the bad guy here. They are being asked to do something extra, they are going to charge for it. That is generally how a business works...
All cell phones (at least those sold in the USA) have location tracking built in. All the wireless providers, then, are gatekeepers of this information. Nothing is changing here in this situation except that AT&T is offering to provide extra information to you and your friends' phones assuming everyone has opted in
Honestly, this hysterical anti-AT&T bias that clouds everything iPhone is getting a little annoying.