What people are going to find out is that the PS3 will be a VERY expensive platform to develop games for. Not only does it have the most power (and thus require the highest quality art assets, which already account for most of the money that goes into making games), but that power is very difficult to "unlock," requiring a lot of custom code that is completely platform-dependent.
Games that are written for the PS3 and take full advantage of it will blow us all away visually (though they won't play like that Killzone trailer or the FFXIII trailer, which ARE NOT GAMEPLAY, PEOPLE), but they'll also cost $50 million or more to make. They'll require specialized programmers to write for the two different processors in that box. They'll require more time spent on art and technology to make that art extra shiny. And none of that extra work would show up on the other consoles.
This will probably mean a higher percentage of exclusive titles for the PS3, but a lower number of titles overall, since small developers simply won't have the resources to make them. I'm not sure how the smaller Japanese houses will react to this, as the PS1 and 2 have basically been their bread and butter for the past 10 years, but I hope that some of them will go to the Wii as their platform of choice.
Basically, at least in Japan, I see the Wii taking over as the platform that experimental games (Katamari, etc) go to and the PS3 will be where big budget sure fire hits go. Over here it might be the 360, due to the larger install base and the ability to get small games through Live! Arcade. Or maybe I'm wrong, and developers will be okay with making games that don't take advantage of the PS3's power. That would also be an interesting first.
It's going to be very odd having such disparate power available -- I'm betting there will be very few games that come out for all 3 platforms, because it will be so difficult to maintain a similar look.