I just had one – with the company right next door (our ex-network guy works there). I didn’t really think it was a big deal, right up until they started asking me questions. Then I remembered how long it had been since I’d opened a programming book. Why would you use an interface vs. an abstract base class? I blanked – gave an answer somewhere in the ballpark of the correct answer (this). Has it really been three and a half years since I did one of these? Hopefully the next one will go better – I’ll cram beforehand.