Service Pack Cleanup Tool
Bundled with SP2 Beta is the so-called Service Pack Cleanup Tool, also known as compcln.exe. This little tool removes older versions of system files replaced by Service Pack 2, saving you some valuable hard disk space.
A caveat about the cleanup tool: Once you run it, there's no going back. You can't roll back to Service Pack 1 without erasing your hard drive once the cleanup tool does its thing, so make sure you really want to stay with Service Pack 2 Beta beforehand.
Before running the cleanup tool, I noted my test PC's free hard disk space: 44.4 GB. After running the cleanup tool, the drive's free space increased slightly to 44.8 GB. However, over the next few minutes, free space actually decreased slightly, to 43.9 GB.
To rule out the possibility of virtual memory affecting the disk's free space, I restarted and noted the drive's free space again: 44.0 GB--still slightly below where I stood before running the cleanup tool. After a second restart, free space stood at 45.0 GB. Long story short--you may or may not notice some increase in free space, but don't expect miracles.