Here's an article about a fellow who put a CF card in a Powerbook 150. Apparently the PB150 has a built-in IDE bus, but he still ran into problems. The amazing thing is the fellow had the software savvy and resources to solve the problem. With his skills there are a lot of cool hacks we might do...

I think I originally saw the link to this article in another thread, either here or on Applefritter.

http://www.cosc.canterbury.ac.nz/greg.ewing/hardware/pb150/

In his case the CF would not work with his Powerbook because it reported back the wrong type of ID. However, from the description, it sounds like this issue may be specific to the PB150 and any machine with ROMs using the same or related IDE driver firmware.