So what happens if some kid possessed of a brain goes, 'I think I'll just register another Hotmail account on my friend's non-MSN 8 machine and port my contacts over'. Since this is a new account, the old restrictions (I assume) wouldn't apply. If this was possible, can you see parents paying for the product?

In another big change, "We're going to have co-existence with MSN Messenger and Windows Messenger on XP," Grothaus said. "If I'm running, say, Windows Messenger in my corporate environment, I'll also be able to run MSN Messenger 5 and be logged in as a separate Passport"--Microsoft's online authentication service. "Today, you can't."
The funny thing is, there is a patch for the current MSN Messenger that lets you do just this - except it lets you have as many instances of Messenger as you like. From the article, it sounds like they have never heard of it.

http://www.mess.be/

-toad