• MCMS 2002 was processor licensed only.  It didn't matter how many end-users you had, the cost remained the same.
• SharePoint 2007 can only be server licensed (instead of processor licensed) for 'internet sites'.  Specifically, that option does not allow you to create content that will only be accessed and used by internal users.
• The 2 points just listed mean that you will now have to buy CALs for all your users!  If you have a few thousand users, your costs may only increase by double or similar (depends on your MCMS architecture).  If you have tens of thousands of users, that will probably represent an increase by typically one or more orders of magnitude.

This is a BIG DEAL.  We have at least one customer who may consider moving off the MS stack as regards web content management as a result.  Why, oh why, couldn't Microsoft just let organisations make the choice, as they do today with SQL Server, between CAL and processor licensing?  It just starts to look like a device to squeeze more money out of medium -> large customers... or maybe a less cynical take would be that it's to up the profile of MOSS in line with the cost and so force businesses to realise the potential value in the product?  Who knows, but there are alternative approaches that would have made my life easier :).

Incidentally, if you have Software Assurance on MCMS and you're in an intranet scenario, you may be okay.  This page mentions an upgrade option for this scenario that translates a MCMS processor license into a MOSS server / CAL license(s): http://office.microsoft.com/en-us/sharepointserver/HA101655351033.aspx (look under upgrades).  However, I can't find any information on the detail of this yet, but if I do then I'll post it here.

Update: Apparently for customers with MCMS Enterprise Edition and Software Assurance, 1 processor licence equates to 250 SharePoint Enterprise CALs - if this isn't enough then you'd need to have further discussions with Microsoft.  If you don't have SA, there's no upgrade option.