The python Zip library does not preserve timestamps when extracting from zip files. While I could patch it, I dont care enough to do so. If you do, the code is in calibre.utils.zipfile.
EDIT: If you do decide to add that functionality, remember that zip files dont store time zone into on their timestamps. So you essentially have no way of knowing what time the timestamp in a zip file actually is
Last edited by kovidgoyal; 05-30-2011 at 11:13 AM.