I think its a good idea they have going, for me it would depend on the type of pay to play model they will use. I'm not really enthused about a subscription model (i.e. $15 a month to play from a selection of titles), since I would rather have a 'pay to own a copy of' type model (i.e. pay $1-2 for a copy of super mario bros which I can play whenever and for as long as I want). Or maybe some sort of hybrid
I think it would be very attractive if they added community and online type features to these retro titles especially if other companies like Sega and Capcom sign on. After seeing a few references XBox Live Arcade, I was thinking it would be awesome if we could see some more recent retro arcade titles, like being able to play the original Sega Rally or Daytona games online, or maybe online tournaments of the Street Fighter Zero/Alpha series etc.