That would seem sensible, but the beta kernel indicates a SI4713 chip for FM TX, and a BCM2048 for FM RX. The BCM2048 is BT 2.0+EDR, but the N900 specs say 2.1. Confusing much? I suppose it's possible they switched at the last minute, and this would also explain why FM RX is not supported.
Oh well, maybe one of these days we'll finally see some dmesg output...