Mobi2Kindle

Mobi2Kindle - Read MobiPocket DRM'd books on Kindle.
Mobi2Kindle is an AppleScript wrapper. Due to the reliance upon AppleScript, it is for Macs only.

You can then add this PID at a Mobipocket vendor site and redownload books with Kindle's PID enabled. It's possible that some vendors will refuse this PID, as it has an asterisk in place of the traditional dollar sign (Fictionwise works fine).