Not to fuel the fire, and I'm sure the IBM microdrives are all Michael says they are, but the price differential kind of makes the issue a moot point. You can get 1gb compact flash from the following link (a 5 star store on Yahoo Shopping) for under $220...20 bucks more than the microdrive.
You convinced me earlier about the microdrive reliability, Michael, but I'll pay the extra 20 bucks (as long as San Disk is a good compact flash, that is) for solid state, even if it's just for false security :-)
http://shop.store.yahoo.com/erwincomputers/san1gbcomfla.html