here with an update (reposting this from my message on palms forums)
SOLUTION: Alright guys, found (correction, my helpful brother found) a solution to the problem. I got the Pre on June 6th and had this problem about a week later. I returned the pone and got another one. For hardware reasons, I had to get another phone after that. Long story short, after having the replacement for about a week, the speaker and mic cut out on this phone too.
We've began researching this for a few days and pretty much decided it was a software problem, and may or not not have been caused by Pandora. The general online concensus is that the phone continues to think that the phone is in headphones mode (either from pandora or just plugigng the headphones in[idk if third party headphones play a part or not]). Im not sure where the post came from, so if you wrote it originally, feel free to take credit:
" I've posted this on another thread but figured I'd post here as well. I've been having the same issue (in which the phone app is still showing a headset icon in the bottom left). The above instructions didn't work but I figured out another fix. in the phone app I called my voicemail with my headset connected, then clicked Mute and unplugged the headset. It immediatly started working as advertised. Then just to test I went into the Music app and Pandora and they worked fine as well. Hope this helps"
IT WORKED. Immediately after trying this I got sound back form the speaker (and the mic worked), after having to use bluetooth for almost a week.