If so, how did it / does it go?
Hasn't happened yet for me, although my parents are visiting this weekend and may well encounter my gf's parents via Skype - I'm really not sure what they'll make of each other.
Two of my best mates have been together for years and are from quite different backgrounds. Her dad is a mechanic and his dad is a city lawyer - I've seen them all together, and her parents suddenly become all formal like they're meeting the queen, while his parents try to be all casual and matey. It's one of the most awkward things in the world.