It's inevitably going to be the future of games and is already happening. The MW2 Rubin use's is already present in FIFA 10 with buying better stats, I'd assume is in other EA Sports titles and the pre-order bonus for Blurr is the same sort of thing. Companies are still figuring it all out, as it's a completely new avenue of money making avaliable to them, but come next-gen it'll become much more standard.
They seemed to miss the other big money spinner though, which is dynamic in-game advertising. I think the much more likely model will be something like free to play, but you get adverts thrown at you in loading screens and such like - however you can either subscribe to rid ads and get extra content of 'buy' some sort of DLC to get rid of ads and get new content.
I'm iffy on whether it'll be a good thing or not, the £7 or whatever some of my mates pay per month for WoW may sound expensive but for the time they get out of it it's a bargain, effectively paying what they would at the cinema for 50x the amount of 'entertainment'. It's only a matter of time until longer games cost more - in some shape or form. It makes sense really though, afterall why would a game you play for 5 hours cost the same as something you do for 100?