I've not tried compressed air mainly because there's nowhere for the hair to go but further in (then I'm screwed).
It looks like the fan comes off, but the plastic is harder than it looks, and doesn't want to bend enough to release the clasps. I was afraid to use a screwdriver. I don't know what damage that might do.
Not to mention this is inside a tower case with wires, PCI cards, AGP card, RAM, and 2 HDs, 2 more drives, etc etc. One slip with screwdriver = dead something-or-other.