Everything in my apartment seems to collect a lot of dust.
My workstation PC collects the most between the twin intake fans, push/pull CPU fans, etc. It's a regular vacuum cleaner. I had to install dust filters.
The only thing that gathers more dust is my vacuum cleaner. It does not play any games though.
The PS3s suck in a fair amount of dust, particularly the one that's on every day.
The 360 doesn't show dust (original matte white), which is not to say that it's not there.
Incidentally, the Wii gathers the least dust. Small profile, low heat/tiny fans and most importantly; it's never turned on.