Just FYI, to motivate myself to get this done, I'm giving a talk on  
this stuff at OSCON this year.
I'm currently revisiting my work-in-progress for BridgeSupport <http://trac.macosforge.org/projects/BridgeSupport 
 >, which allows the bridge to dynamically bind to any framework that  
has an associated bridgesupport xml description file.

OSX 10.5 ships with a complete set of bridgesupport files, and it is  
possible to download and build your own bridgesupport files using the  
tools at the location I mentioned.

--Wez.