No updates for a while now, but I just saw the linux-2.6.10-mh3 patch on bluez.org.
Apparently it has better HCI raw mode, which might make those extra keys work!
If anyone tries this before me, please let me know!

Apparently the 2.6.10-mh3 didn't work that great. Went from 2.6.9-gentoo-r4-mh4 I think, to 2.6.10-gentoo-r6-mh3 and apparently the extra-keys (multimedia, etc) died. Haven't thoroughly verified this, though.

I've been thinking about updating the bluez-libs and bluez-utils to see if 3.6.10-mh3 or the newly released 2.6.10-mh4 would work better.
Will keep you posted.

2.6.11 and 2.6.11-mh1 are out! Give 'em a shot and let me know if the problems in 2.6.10 are solved!

2.6.11-gentoo3-mh1 didn't solve any problems with the multimedia keys.. stick to 2.6.9 if you need them.

According to Luke <gar at reapl dot net>, 2.6.11.5-mh2 restores the functionality of the multimedia keys.
I can also confirm this. Also updated 'Summary 1' with a note about kernels.