Gary and others...
I believe (and I could be wrong) that an example of this from another
company is none other than Microsoft. Don't they license exchange by
seats? Yes, you can buy more and put more users on it, but you still have
to purchase it.
Yes, Exchange is licensed by the seat... but this is a little different:
This is akin to taking a PC which has Windows98 on it, and converting it to
NT without paying for the license - and vice versa. Win98 costs about $100
retail and is single-seat. NT is about $700 and each seat is additional
(about $35/seat if memory serves correctly).
Joe