I've started working on such a thing (although the first format targeted is .tar.bz2, .zip should not be much harder to read). I'm still trying to sort out how to use git for boost contributions at this point. gitorious was apparently broken when I tried to clone the svn branch. If I still can't do it, I might just push this to github which works for me.
Did you check the hamigaki library? There are several archiver supported: http://hamigaki.sourceforge.jp/doc/html/archivers.html even compress/uncompress of tar, zip (zip64)! Unfortunately all in Japanese, but C++ is international ... If I would have time and knowlege I would like write a virtual file system using this with the vfs API from http://commons.apache.org/vfs/ but I'm hobbyist. Regards Olaf