Q9505 to replace the Q9400
It looks like Intel is going to be putting out another socket 775 Yorkfield 45nm Core 2 CPU this generation; simply rebranding to the Q9505 and knocking down the L2 cache to only 6MB, it will share the same specs as the Q9550.
The Q9505 should cost around $200 US when released and its sole purpose is to replace Q9400. Currently the Q9550 sells for around 230 US and you get double the L2 cache, which will give you a better performance out of the box.
For the dollar conscious consumer this may not be a good deal, but for the enthusiasts and gamers, the Q9550 is worth the few extra dollars.