My MacBook fan was running too often (and too hot) for my own good, so I decided it probably needed a good cleaning.
I used the ifixit guide for removing the fan and was 99% satisfied with the instructions. The only problem I had was when I got to the final step (19), removing the fan. The only advice/warning was something about not ripping the black tape. Well, rip the black tape I did, but at least I got the fan out and was able to clean it. :-)
I'm still not sure how to go about not ripping the black felt tape, but even if you do, it didn't seem to be a problem for me.