protobuffers know what files they will generate for zips/jars.

Preliminary support for compressed archives as sources. Currently .zips, .jars, tars, tar.gzs, and tar.bz2s work for protobuffers. Code is fairly extensible, with generic functionality in zipped_sources such that not much code is needed in protobuf_gen (or other targets in the future).
Really? Trying 'hello'[30:] on the command-line interpreter for python 2.7.6 just returns the empty string.