BTW, we've just been dealing with the fact that Blackboard 6 'secures' it's digital drop box via obscurity (a random number added to each filename, and that's it) and thus has NO security to keep students in computer labs from browsing each other's files in the drop box via browser history!
Moodle's system of double session checking for all file access is miles ahead of it's $100,000/year "Enterprise" competitor (frankly I'd be embarrased if I was a Blackboard programmer
).