http://docs.google.com/images/doclist/icon_7_punch_large.png

>>A "punch" is a Google Docs filetype, just like a document, a spreadsheet or a presentation.<<
via GOS http://googlesystem.blogspot.com/2010/07/google-punch.html

It might be a code name for new Google Docs presentations. Just like Kix for new version of document.

Or not: http://techcrunch.com/2010/07/26/google-punch-2/