Oh yeah, it will most likely cost money.
I don't believe it should cost money (based on what has been released on 10.6 so far).
They update the kernel to finally be 64-bit compatible and to be multi-threaded.
Quicktime X is a "filler" to add on the list. It's nothing special IMO. I personally don't use Quicktime (unless I absolutely have to). It seems that Quicktime X will fix many of the crashes while playing back videos, although, IMO, it's something that should have been fixed a long time ago.
OpenCL appears to be a new API for developers, and the only real "new" thing I see on the list. What I mean by this is that I can't think of any API for Windows or Linux that aims to do the same thing. This is the only real thing that is something that belongs in a new release that brings something to the table that is not available in other OSes.
While I feel that OpenCL, multithreaded 64-bit kernel are great things, and things that are worthy of a new OS. I feel that the other thing they tout, efficiency, performance, and stability, are not things worthy of a new OS. Instead, they are things that I would expect to see in an update, and these are things that SHOULD have been focused on in Leopard during development. Instead, Apple chose to focus on features, and now they plan to hit us up again by charging us for what should have been Leopard. I'm not trying to minimize OpenCL and a multithreaded 64-bit kernel. Those are great things. But, if they're dedicating much of this release towards stability, efficiency, and performance, it should have also been present during the development of Leopard.