I don't have this problem and I use speaker phone all the time. I do not have a case though. It shouldn't be doing this. I would call Verizon. Not sure if its a hardware or software issue. They should be able to help.

 

I have the exact same problem with my Droid 2 (horrible noises for people on the other end when I'm using speakerphone). I've noticed that it only happens when I move the phone -- if I leave it sitting on a stable surface and don't touch it, then speakerphone quality is okay.

I also have a hard case (some generic brand) on it. I just now tried taking that case off, and it seems to correct the issue. So I'm guessing the case and the microphone weren't getting along.

 

If the problem keeps happening and you can recreate it at will, take it to the store and show them, if they can't fix it they should replace it.

 

I have been having an issue with the sound quality on my end when listening to recorded greetings. Phone speaker breaks up erratically. Well today I was cleaning my phone and broke my case/holster so I'm running the phone naked. I have made some of the same calls without the case and the sound is much better. Its interesting that the case can make that much difference but it really seems to.

 

I have the same problem. People can't hear me when I phone out and I put the speaker button on, but I can hear them fine.