I was surprised to find that even though many of the Pocket PC phones have Bluetooth headphone support, you can not direct Media Player to output through the Butooth headset. I was told that was true for the 6700 from Sprint & the MDA from T-Mobile. At least that's what T-Mobile tech support told me when I got my new MDA home and tried to set it up. I got the same answer from the Sprint tech when I asked at the store.
If anyone knows this not to be true or has a workaround please let me know. I loved the MDA phone for the 3 days I had it but could not accept this limitation. I walk to work and like to listen to Podcasts and such as I walk along.