I know, this has been asked a few times, but mostly for Xcode 3.x. For the iPad, I have two projects both living in a common workspace
In general Xcode 4 seems to discover the dependencies automatically as the Edit Scheme sheet implies. Other developers have mentioned that the dependencies are not automatically discovered and require explicitly listing them:
So, Edit Scheme -> Build -> add targets from your workspace.
As far as the static library header files go, Xcode 4 seems to have a problem, at least with code completion and syntax highlighting. The only way I can get either to work properly with classes in static libraries to to drag a copy of the header files in question to a location into a group folder in the main project. Note that you should uncheck Add to Target... That takes care of the syntax highlighting and code completion. The rest should be handled by giving it the proper header search path. That would be User Header Search Paths = $(BUILT_PRODUCTS_DIR) - depending on how you set up your locations preferences.
See: this link