Depends on what you're doing. The 27" I use is really quiet, even more so than my MacBook.
exactly why im confused, running tweetdeck, firefox, safari nothing heavy. I just touched the back and it's really hot, the top is just burning.
Try restarting the dock, or deleting the .plist for it, that may help. Looks like you just encountered a glitch which is conveniently sucking up all of your CPU.
Are you using Parallels 6 and just upgraded to OS X 10.6.8?
"ISSUE
After updating the Mac OS X to version 10.6.8, with Parallels Desktop 6 for Mac installed, the Mac systems Dock process may start consuming 100% of the CPU core. This results in slower than expected Mac OS operations."
http://kb.parallels.com/111541