i tried searching, but didnt have much luck.
I am wondering if its possible to change the priority of the phone app on the N900. I would like it to be like top priority (or close to it) so that when i get a call, it actually ...well, works. even while if i have facebook open and some IMs in the background.

Anyone know how, or if its possible at all?

omhd already takes care of this by using cgroups to set certain processes to high priority than others.

You could look at switching to a kernel with BFS and you can use schedtool to manually set processes to FIFO, round robin or "real time" slicing.