Phone will not vibrate for incoming text messages
I had a rom that failed to vibrate certain "very short duration vibrations" (or those of low strength vibrations). I am not sure if its just a hardware limitation of my phone or the rom in particular, but you could try an app like Handcent for now and play around the vibration settings in there. Handcent SMS allows you to fine tune the vibrations, adjust the intervals between each vibrations in milliseconds etc..