<p>Is anyone using the OSGi Bundle Repository and what for?</p>

I am using it!
When you develop an osgi bundle and the target platform doesn't include the libraries (jar/bundle) your bundle relies on, it needs to added to the target platform. you could either repackage your jar to make it an osgi bundle or just download the bundle from the OBR.
Eclipse also provides an OBR call
Orbit
, and springsource one is called
Enterprise Bundle Repository
.