Watch the video hereDust fans can greatly affect a console's performance.
They also generate a vexatiously louder than usual noise emanating from your powerful machine.
If you want to keep things nice and tidy and/or want your fans running smoother, you'll want to have a quick look at this clip.
It's basically a video instruction about running a fan test on your PS3 which also blows out the dust and essentially cleaning it up. What's nice is there's very little effort involved, so you can actually do this every day. Just a warning though, it's only for 40GB models.