I had some SVN problems, and figured it would probably be faster to do a full new checkout rather than trying to figure out the mysteries of the .svn folders. But then I realized that I had made some uncommitted changes in the old folder, and started brushing up on my unix diff commands. While looking for some hints on this, I came across this Mac OS X Hint on how to compare two folders. The little program FileMerge is included in /Developer/Applications/Utilities. Works like a charm!