LOL @ all the comments of the PS3 looking better.. Sometimes I wonder what it is people look at.
Ok I'll back up my claims. First of all, most of those pictures are not like for like. Therefore it's kind of hard to make a good comparison. However, there are some evident things that can be seen regardless.. Let's start with this one:
http://www.videogameszone.de/m,browser_fullscreen/?pic_mode=fullscreen&pic=/screenshots/original/2010/02/BioShock_2_Vergleich_PS3_vs_Xbox_360_Screenshots_01.jpg&name=BioShock%202:%20Grafik-Vergleich%20zwischen%20PlayStation-3-%20und%20Xbox-360-Version
Look at the reflection in the water. The PS3 version is clearly lower res. Now look above the reflection to the circular thing the plants are in. Look at the edges. What do you see? PS3, no AA, X360 2xAA.
How about this one:
http://www.videogameszone.de/m,browser_fullscreen/?pic_mode=fullscreen&pic=/screenshots/original/2010/02/BioShock_2_Vergleich_PS3_vs_Xbox_360_Screenshots_05.jpg&name=BioShock%202:%20Grafik-Vergleich%20zwischen%20PlayStation-3-%20und%20Xbox-360-Version
Look at the lightning effects. Again, PS3 version is clearly lower res.
And this:
http://www.videogameszone.de/m,browser_fullscreen/?pic_mode=fullscreen&pic=/screenshots/original/2010/02/BioShock_2_Vergleich_PS3_vs_Xbox_360_Screenshots_09.jpg&name=BioShock%202:%20Grafik-Vergleich%20zwischen%20PlayStation-3-%20und%20Xbox-360-Version
The stairs are clearly sharper on the X360, though the position is too different to make a good comparison, that's the most evident in that pic.
Truth does not fear investigation