UPDATE (06/26/2009): In the meantime, another, major problem has been found out: the encoding lag. See the just-added UPDATE section in the original article.
Originally written: Unfortunately, there are two major problems with the stereo Bluetooth (A2DP) support of iPhone OS 3.
1.) Many of you have already posted the previous/next remote controls not working. This, unfortunately, is a fundamental problem with the AVRCP implementation of OS3. Hope they’ll fix it in a next update.
2.) I’ve found a very hard-to-track and really annoying problem.