There are simpler solutions to find out what you are sharing than to browse your files. If you run a few ultrapeers you can extract the all you need to know from the queryHit traffic passively and within a couple of hours you will know what thousands of users share (even those servents that do no support browse host).

If you wanted to make gnutella secure, you'd have to proxy all file-transfers and rely on Push-like mechanisms to start all downloads. It's possible and not too complicated (you don't even have to remove the ability to browse hosts to achieve anonymity) but all uploads and downloads would only be half as fast and the download mesh would not work nearly as well. That is a price I'm not really willing to pay. There are other networks that already offer that kind of security you seem to seek, like Freenet, WASTE or GnuNET.