Originally submitted under Rubyforge by Jarred Holman. Paraphrased:
Allow any readable, IO-like stream to be used as an archive source by Archive::Zip.new, even non-seekable streams. Specifically, allow for the use case where a ZIP archive contains an embedded ZIP archive which can itself be opened and processed without first writing it to disk.
+1 for this. RubyZip supports it. Also writing an OutputStream.