I bought a Seagate 5GB microdrive and formated it ext3, it needs frequent re-insertions to get it to work. I can't save my email there like I could on my cf card, all in all I'm not really sure yet, this weekend I may unlock it's secrets and be perfectly happy, but right now, I'm not sure.
If I get good results, I'll give it a thumbs up... for now, it's thumbs sideways.