iPhone Apps built for the simulator are stored here:
/Users/<username>/Library/Application Support/iPhone Simulator/User/Applications
Is it possible to copy the <GUID>.sb and <GUID> directory and install them on a different computer (with Development tools installed)?
This would be very useful for testing/demoing with out having to buy iPhones for all the managers and external clients.
Yes, if you send those files to another person, and they put them into that directory, they can test the applications in the iPhone Simulator as well :)