The one thing I know is the license has teeth. If you exceed the license it will shut down. You bought yours so only you have ready access to your license. For example the license for 2003 has so many variations that it would be a wild guess to see what you have. Even the OEM versus retail versions differ on the install count.

So the answer is 'no', this is not the case for prior versions. We can expect the same for Office 2007.

If I need to install Office on many machines I install Open Office first then wait for someone to complain.