I teach English at a small university in south-east Sweden, and I've been running a university course exclusively in Second Life in each of the last four terms. The course is called Business Talking and successful students get 3 European Credits for it. Students apply for it in exactly the same as for any university course in Sweden, and we haven't been advertising it at all, mainly to keep the student numbers down to a level we can handle!
We started the course this term on 17th September with our usual cocktail party, where students of mine were paired up with students from a US university (so that my newbies could get help directly from English-speaking slightly more experienced students).
Last night we were on Course Meeting 2 (out of 5) and it was just as much fun as usual! I actually ran two sessions yesterday, because I have a couple of students who're in China IRL, so a meeting in the Swedish early evening is in the middle of the night for them. I'm in a 'typical' situation this term: the only people who're in Kalmar (my base) IRL are exchange students, who're actually from Austria, Korea, China, Russia, France, etc, etc. The Swedes are all somewhere else - from Barcelona to Shanghai (and in a few other places in Sweden).
The first two course meetings are practice sessions (partly to get them accustomed to Second Life and partly to give them practice in speaking English) and the last three involve assessed tasks. Yesterday I was giving them practice in interrupting, interjecting, asking questions, etc, to show your listener that you're actually interested (Swedes have a tendency to be deadpan, which is a bit off-putting). I use an exercise called 'Picking out the Porky' where I tell them five stories from my career as an English teacher and they have to work out which one is a lie (pork pie = lie in Cockney rhyming slang!). They always think that being threatened with being shot by Angolan soldiers is wholly fictional, and the story about being an undercover Iranian in Istanbul gets them too (but those ones are both true!).
This is an exercise I learned from a physicist who used to gather his research team each week for coffee on Fridays when one of them had to relate what he or she had done that week, with the insertion of a plausible lie. It's a great way of getting people to focus. Picking out the Porky works really well in SL.