of those 350 developers most of them are 3rd parties like Komnami, Namco, Square, EA, THQ etc.......
Of those 350 developers maybe 20 or so are SOny 1st party studios, and 2 Sony 2nd parety studious Naughty Dog and Insomniac.
Yes we have not seen the majority of games being developed for the PS2, but my bet is a solid portion of those 350 developers will develope crap compared to the gems the big boys will put out. The strange thing is there are alot of people out there that purchase these titles. XBox will have a similiar fate with there high count of 3rd party developers, it attracts the masses but kind of shoots the quality ratio in the foot.