The only changes to the Drives that I've heard of are minor convenience items:
1. The pedals have a pad on them -- should be more comfortable bare footed (and look neat too).
2. A small bungee holds the pedal in a position where you can put your foot directly on it without having to flip it over each time. This gives a quicker, more convenient access to the pedals.
The big changes for the Oasis came in '09 -- redesigned hull bottom, Click & Go Drive latch mechanism (all models), rudder deployment/retraction lines (all models) and V2 Drive sprockets (all models). For '10, probably small changes like improved mesh pocket bungees and as you mentioned, redesigned seats.
