[Xmonad] Ideas on configuring workspaces?

Firstly, thanks for the tips on getting XM working on FreeBSD. I got it working after upgrading to FreeBSD 6.2 (required to build GHC 6.6) and getting Cabal from darcs. Finally a window manager a non-X-guru can (mostly) understand. I have been looking at having XM configure my workspaces, rather than doing it manually after prelaunching apps in .xinitrc or launching them from the keyboard. However, I don't have a clue how to correlate the app's windowID, when they decide to map themselves, with any data structures I might build in Config.hs. Does anyone have any clues about what info is available through X that might help? Dale Jordan