I also say yes for an AirBerlin Forum. For instance for bmi we have a separated forum, too. The situation of AirBerlin in Germany is kind the same as it was with bmi in the UK.
Germany:
Lufthansa flag carrier and *Alliance member
AirBerlin 2nd largest German Carrier becoming OneWolrd Member
UK:
British Airways flag carrier and OneWorld Member
bmi 2nd largest (?) british carrier and *Alliance member
In addition AirBerlin has a successful operation outside of Germany with a hub in Palma de Mallorca.