So fkrauthan (in #symfony on freenode) ran up against an interesting issue w/ regard to generating paths to other bundles assets.
I don't personally know much about the problem area specifically, but I worked with fkrauthan to develop a hack that got around the problem.
So, please, take a look at the github repository and chime in your two cents. I'm almost positive there is a more elegant way to do this, but we had no idea what that was.