10.5 ships with uppercase menu items in the Finder's sidebar, similar to recent versions of iTunes. To make things lowercase like they should be, do the following. First, navigate to (or copy and paste the following into the Go » Go to Folder dialog):
"SD5" = "Devices";
"SD6" = "Shared";
"SD7" = "Search for";
"SD8" = "Places";
Save the file (entering your admin password if asked) and log out and back in or open Terminal and type killall Finder to relaunch the Finder and see your changes.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20071030001816718