I highly doubt anyone would be buying a ps3 solely to get killzone2. At least everyone around me that I know that's giving praise and urging me to get it already have a ps3 but I'm sure it will get a small bump to at least stop year over year sales decline. I'm not so certain it will pass the 360 for the week however and definitely not the wii.
“When I was 5 years old, my mom always told me that happiness was the key to life. When I went to school, they asked me what I wanted to be when I grew up. I wrote down “happy.” They told me I didn’t understand the assignment and I told them they didn’t understand life." - author unknown