It’s been bugging me for a while now that, ever since upgrading to Xcode 3.2 and Mac OS 10.6, the list of recent projects in Xcode’s initial window, and in its “Open Recent File” and “Open Recent Project” menus are all blank.
Thanks to @pimpinglen, I found the answer here: the “Documents” value under “Number of recent items” in “System Preferences“‘ “Appearence” item (phew) now applies system-wide to all Cocoa applications!
I had this set to “None” in OS 10.5.8, and this settings remained.
One solution to this problem is to change the value on a per-application basis:
defaults write com.apple.Xcode NSRecentDocumentsLimit -int 10
… which keeps the system “Recent Items” menu tidy – but does require manual setup for each application, and is somewhat non-obvious to change from then onwards.