The fact it isn't part of the kernel also indicates to me it is nowhere near ready for prime use.
Thats a really big can of worms to pry open. My mailbox doesnt need the flaming!
If you want a journalling fs that doesnt hog your cpu and is still slow as a dog (so not ext3), try XFS or even JFS.
From what i have read JFS may not be in the kernel much longer. Dont know, worth someone filling me in.
Im running XFS on several machines with excellent results. Less disk activity, less cpu over heads and better all around performance.
Installs with the debian installer (although the deb installer still insists on LILO, even though grub works fine. but grub annoys me anyway) Give it a whirl Dean -- http://fragfest.com.au