People hang out with who they like. For example, except for very few, none of my Nepali friends are of my own jaat. And they are all from different jaats. As for these cultural programs, that's exactly what they are, cultural programs. Those events are held to showcase and preserve our traditions back home. And as far as I know, those events are open to all, not just for that particular jaat. So, good for them. As for the facebook and other community sites, people do what people wanna do.