Will SP1 change that? Not at all, according to a recent study. It was found that after installation of SP1, the overall application compatibility of Windows Vista remained exactly the same. However, this is not the only study to agree that this could be a positive thing from the perspective that if the Service Pack has no effect on the applications being run, then it's a better indicator that it will not break any of the current compatibility base, and make for an overall stable release. Back in the day, many people were burned and irritated by XP's SP2 when it rendered many programs non-functional.
Ultimately, it could be argued that it is the software vendors who develop these programs that are responsible for ensuring Vista compatibility. I don't blame Microsoft for not trying to turn Vista SP1 into a series of workarounds to get other programs to work. If they concentrate on the core functionality of the OS, perhaps they can save what initially appeared to be the spiritual successor of Windows ME.