Mail-like Favorites Bar as seen in OS X Lion

I'm interested in implementing a "Favorites Bar" in my Cocoa application in the same way that Apple have done so in the new version of Mail in Lion. I thought I had read that this was a standard control now, but I can't find any indication of this.

I've recently seen a similar control appear in the Evernote client when they claimed "Lion-ification of Evernote" which caused me to wonder was there a standard control out there.

So can anyone point me to docs for such a standard control, or can anyone recommend other开发者_JAVA技巧 implementations out there for replicating this functionality?

Have a look at MGScopeBar by Matt Gemmell: http://mattgemmell.com/source