I don't think the PS3's peak year is 2010. Personally 2011 is more likely.
My thoughts on this is based on the fact that the PS3 is just now performing like a PlayStation platform. Tons of games coming (a healthy amount of exclusives), great features and services and PlayStation Network expanding. So I feel that with this tremendous amount of momentum that has swung in the PS3's favor in the past 7 months it's "peak year" will be next year.
Even more games will likely be released next year. More features will release. More services. More importantly MORE GAMES.
2010 will be fantastic for the platform, but it's not the "peak year". Way to much potential left in the system.