I'll chime in here: I haven't had any call quality issues with my droid. My wife is on her third LG Dare - the first died an untimely death due to a dead power button (lasted until she forgot to plug it into the charger; no way to get it to turn back on). The second one was turned in a week after she got it, because the mic was bad, would sometimes cut in and out, and generated static sounds. The third one has been fine.
As for the droid, if it's an occasional hardware issue, I expect it'll get worked out simply by the bad ones getting returned. If it's software, I'd expect more users to be having the problem.
Yes - there are a lot of users reporting the problem, but it's likely a drop-in-the-bucket compared to the total number of happy droid owners (like myself and many others in this thread). So I can certainly understand why some people are assuming it's the tower, or a hand, hair, etc.