If we run our software here using the same front end, we don't have to modify it to make a release. That is, we wouldn't write it to assume use of the Sun grid engine and Sybase if we were using the cloud. (I hope.)

Yes, if we said, "Here's our software, which will run on the cloud provided you have a Sybase license," that wouldn't be a huge improvement.

Also, users usually can't run these programs at home, since they require dozens or hundreds of computers.