An updated document on WHDC lists the new DV features for Vista. Having used them, there are some great new additions to the verifier. One of the best features is the ability to start verification without a reboot. It has its limitations, but it is still a huge improvement.
Another feature that I requested and made it into the Vista is that you can get the ASSERTs/stops on releasing a tag that was not previously acquired on a IO_REMOVE_LOCK that was not acquired on a fre build of the OS. Normally these ASSERTs are only present in a chk build of the OS itself. Since not that many driver developers know to run a chk build of the OS, many developers were not getting the debug feedback on their misuse of the remove lock. To get this functionality you still need to run a chk of your driver (or more specifically, the chk size of the IO_REMOVE_LOCK structure).
There are new bugcheck subcodes 0xD5 and 0xD6 (MSDN contains this info as well) for DRIVER_VERIFIER_DETECTED_VIOLATION (0xC4) that relate to remove lock verification