Limewire is one of my favourite open source projects, and I was just pondering today if there would be any way to anonymize it to a degree.
I'm no encryption expert by any means, so presumably nothing I say has any chance of working. But I thought it might be worth suggesting.

On to the basic idea, I realize that for an application like Limewire, who's purpose is publishing content, full time encryption would probably not be an option. So I was trying to think if there were any small pieces of communication that could be encrypted with good effect.
What I came up with is the idea of encrypting file requests and responses (if both hosts support it), but not the file transfer itself. As I understand it, Limewire can currently download a file in small chunks, and from many different hosts, so assuming the chunks were fairly small, they wouldn't be enough to provide information on the files being downloaded.

Mostly I was just rambling, and thought it might do some good here. So please let me know why this won't work.