To answer a question on Forrst, a place that makes me happy, I had to discover how to reveal a folder in the Finder. This type of behavior is seen when you right-click an app icon in the dock and choose Options -> Reveal in Finder. It opens the folder that the app is in, usually /Applications, and highlights the app. (Turned out the poster on Forrst just wanted the folder opened, not revealed, oh well.) A little searching and the solution became apparent:

[[NSWorkspace sharedWorkspace] selectFile: folderPath inFileViewerRootedAtPath: nil];

Or for those who are only forward looking (won't support below version 10.6 of OS X):

[[NSWorkspace sharedWorkspace] activateFileViewerSelectingURLs: [NSArray arrayWithObject: folderURL]];