Since there has been no update since the Oct 21, 2010 submission of Calibre 0.7.28 for Portable Apps, I have created and will be maintaining newer versions. I have posted the latest version, wrapped for PortableApps at http://sourceforge.net/projects/calibreportable, and will continue to update it regularly.
Please consider this a request for testing and submission for full PortableApp status as soon as reasonable. Note that Calibre itself is in constant development, but is also considered by the users as a fully released application.
Please address any questions or issues with the PortableApps implementation of Calibre here, or at http://www.mobileread.com/forums/showthread.php?t=133957 .
Thank you for your time and consideration,