I think you're right Steven, it could work IF you used a two part compound and held the tire at a fairly high rpm until the compound cured. Otherwise, like Fix-a-Flat, it might cure unevenly and render the tire out of balance until cleaned out.
Now I'm curious about how that newly US marketed no-flat tire is working out. They started TV ads on it about 2 years ago but haven't heard anything recently. A quick google search brought up far too many to read right now but here are some:
http://www.accidentreconstruction.com/n ... 3100a.html
http://home.att.net/~thetandemlink/arti ... thaneTires
And you've just GOT to read this one!!!!:
Sounds like an incredible show that I wouldn't want to miss!!!