CUPP (pentest) on google app engine
I see a few problems right off:

You'll need to create a web interface to the script
GAE does not allow long running tasks and this looks like it could take a while.  You'd need to recode it to break the work up into chunks.
Outbound FTP (for fetching word lists) is not supported on GAE
Local file write access is not supported (you'd need to convert this to use the datastore)
Do you see any limitations for cupp (http://www.securityfocus.com/tools/7320) running on GAE?