Here's one of the top new features:
#10: The self-healing NTFS file system. Ever since the days of DOS, an error in the file system meant that a volume had to be taken offline for it to be remedied. In WS2K8, a new system service works in the background that can detect a file system error, and perform a healing process without anyone taking the server down.
"So if there's a corruption detected someplace in the data structure, an NTFS worker thread is spawned," Russinovich explained, "and that worker thread goes off and performs a localized fix-up of those data structures. The only effect that an application would see is that files would be unavailable for the period of time that it was trying to access, had been corrupted. If it retried later after the corruption was healed, then it would succeed. But the system never has to come down, so there's no reason to have to reboot the system and perform a low-level CHKDSK offline."