I have this problem with copying files from my local HD to a USB thumb drive. The computer copies very fast... but to a temporary folder somewhere on my system (it doesn't say this, though). In fact, it's not even until I go to unmount it that the system actually starts putting data on the thumb drive (and the little led starts flashing to indicate I/O). While it's performing the copying and unmounting, I can go to the System Activity window and see that the process "pdflush" (and one other that I forget at the moment) have a CPU status of "disk sleep" or something like that.
How can I disable this crappy feature in Fedora 11?