If you use Disk Utility's Repair Permissions feature, you've probably seen lots of occurrences of the "ACL found but not expected" error. Errors of this type are very common, and rather hard to fix. They'll sometimes affect hundreds of folders, usually Applications or one of the Library folders.
When I ran a permissions repair in Disk Utility, I had almost every file on my entire hard drive report an error, and the repair would take about three hours. When I tried to find a solution on the net, most of them either involved doing something to one item at a time, or removing permissions from your entire hard drive, neither of which I wanted to do.
So, I wrote ACLr8, a command-line utility in Python, that scans the hard drive for these errors and then removes ACLs from only the files which are not supposed to have it. I'm posting it here hoping it will help anyone that has had this problem.
[robg adds: I tested this on my 10.5 drive, and it worked as described - it found 10 files with unexpected ACLs, which matched the number found in Disk Utility. After running the utility, Disk Utility showed no unexpected ACLs. As noted by the author, however, use at your own risk.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20090914214952832