Yeah, they have Chris - my i8910 has 120fps slow-mo in half/quarter/8th speeds.

Its nice to have from time-to-time, I won't miss it much though.

There is nothing in the hardware of the N900 that prevents this being implemented, it largely the same as the i8910. The problem will be Nokia's software implementation, they have been very slow in relation to their competition to add things like panoramic mode and face/blink/smile recognition.