Add to the list:
You can no longer directly locate plist and other configuration files through Spotlight. Instead, you've got to go through a series of convoluted steps in the finder window just to get the search to recognize such files. Of course, once you close the window, your hard work is erased, and you'll re-run the gauntlet when next you need a similar search. Apparently, this is because Spotlight no longer searches the Library folders.
I have no idea why Apple chose to make things harder to find in Leopard compared to in Tiger. There's also the issue of how Tiger (in the finder window) sorted search results into categories (applications, documents, folders, etc). No more in Leopard! The first issue is a bigger deal to me than the second, but in general, Spotlight's been handicapped. I do like how it's faster, but taking away options and leaving PUs without means to reinstate them isn't progress; it's a step backwards.