The issue with 3G reception is pushed more to the “fiasco” side when you put another AT&T 3G-capable phone next to a 3G iPhone. In many cases, reception on the iPhone shows no bars while the other 3G phone shows a full 5 bars. This is documented on the iPhone Atlas site. I think this discounts the notion that “all” 3G devices have problems indoors. This is either a software issue or, worse, a hardware issue.
Another suggestion made by users, and then also offered by Apple, is to just turn off the 3G setting on the phone, thereby forcing the device back to the EDGE network. This will, in fact, get the phone working. However, if you purchased a 3G iPhone, live in an area which AT&T shows on their own website as fully within the 3G network, and have to turn off the 3G functionality in order for the phone to work… something is not working correctly. Apple is releasing OS 2.1 on Friday, and hopefully it will address these connectivity issues.