Now that AMD is getting ATI, I am sure that Intel will advise Apple to drop ATI Radeons in favor of NVidia on the next MacBook Pros. I am speculating that the next Merom-based MacBook Pros will have 256MB and 512MB NVidia GPUs along with a Blu-Ray-compatible drive and running on Leopard. 
I am slightly in favor of NVidia only because of its Linux support. NVidia provides binary-only graphics drivers that work perfectly on my Ubuntu Dapper Drake PC. Although it is not entirely open source but it really does not have to be as long as it is free and it works. 
