@Chris CA
As stated in my post, iTunes said my COMPUTER was already authorized AFTER it told me it wasn't and that I had to authorize it - so I dutifully went through the process.
The final dialog box, after authorizing was complete, stated that the computer was already authorized, and the dialog showed only three installs, which is what I had originally, and I never deauthorized any computers or the other OS.
Perhaps before Lion or before the latest version of iTunes, what you stated is true, or if you go through some other sequence, but I followed Apple's instructions in KB Article HT1449. BTW, that article does not state anything about authorizing or deauthorizing your account when moving your iTunes library. Perhaps because I had not yet opened iTunes in Lion it triggered the authorization process, but my point is that after all going through the process they insisted on, iTunes tells me I didn't have to authorize my computer again and my number of authorized computers remained the same.
Wacky.