hah...getting closer

the problem is (at least it was for me) that the n900 doesn't identify itself as a "phone", rather it identifies itself as "other", see
https://bugs.maemo.org/show_bug.cgi?id=7849

when i run this as root

stop bluetoothd
rm /var/lib/bluetooth/*/config
start bluetoothd
start bluetooth-dun

i can get the playbook the recognize my n900 as a phone and then use the tethering screen to connect =)