Its worse getting dropped into $USER_FRIENDLY_EDITOR_OF_THE_MOMENT. It's cool that the sys admin or the distro developer loves to use pico, nano, joe whatever, but I just want to make my change and move on.
I suggest using hg or git, neither of which have a lock.
That's certainly a possibility down the road.
Our tech staff has a gForge installation that has LDAP configured and all the other goop, but only supports svn. Not managing accounts, password resets, and the inevitable extra map from student id jgordon to login SassySystemsHax0r is a big win.
Since it's their first time using SCC, I already have to deal with "but I just forgot to commit!" for the first two weeks. I'm a little worried that with a DVCS, I'd then also have to deal with "but I committed -- what do you mean I have to push, too? Well, can you grade against the local timestamp?" And that will happen all quarter...
ESC : q!
Because you never know when some commandline tool is going to drop you into vi (I teach them about the EDITOR variable, but sometimes you ssh somewhere and, you know...), and you need to know how to get out.
True story: the number one cause of issues with source code control systems is a vi session that the students accidentaly opened, managed to flee from with C-z, and didn't realize was still around with an open file holding the subversion lock and preventing them from committing their source code. I'd say I got 5-10 a quarter (~60 students in each quarter's session).