[ale] DummyQ: What's needed to use "secure flash" w/Linux?

[John Mills]

ALErs -

Do current, off-the shelf "secure" flash-drives (e.g., USB type) work with
current versions of Linux? If so, how does one use them? Are the files
encrypted, the directories, or what? Or, alternatively, are there Linux
drivers that are reasonably transparent to use, that encrypt directories
and/or files of any disk-like device?

Mike's "Encrypt This" talk left me thinking that last answer is 'Yes', but 
I don't remember any candidates.

TIA for any background or pointers.

 - Mills

"That's not encryption - just my *****y typing!"