I wanted to run OpenELEC 3 to get XBMC 12 "Frodo" because cancel works, which is to say that I've never previously been able to cancel actions like browsing a SMB server and I've been running XBMC since it was XBMP. To make a long story short, OpenELEC 2.99.2 (RC2) has nonworking bluetooth. Some have reported success with 2.99.1 but that didn't work for me either. But as of yesterday (20130206) there is a dev build that does work, and I have installed it.
For some reason the official install instructions don't work, perhaps for lack of config.txt. What I did that worked was to install OpenELEC 2.99.2, then delete kernel.img and SYSTEM, and copy in the appropriate files (with appropriate names) from an alternate source of images listed on the Raspberry Pi Install Instructions for OpenELEC. In my case I used the following files:
Afterwards the first thing I think most users want to install is the repositories installer, through which you can install nearly everything else. But let me just leave this here, it links to the repo that has bluetooth tools and mc in it.