Yes, it basically means "How are you?" but the answers are different -- you can't say things like "good" or "okay". Usually people answer by saying "Nothing much. How about you?"

I think anamsc and BuffaloBob all right. Sometimes it basically means "How are you?" Usually people answer by saying "Noting or Nothing much. " A deeper means "What are you doing?" or "What's happened in your life recently?". IF you look Series's Friends. you can find out it. how to answer this question. example 1 Joey:What's going on? Monica: Nothing. I just think it's nice when we're all here together. example 2 Monica: What's going on with you? Phoebe: I got no sleep last night! example 3 Rachel: (to Joanne) So what's going on with you? Joanne: Well, guess who my dad's making partner in his firm? 由于我英语太差，所以怕我说的你不能理解,我用中文大致说一下内容。 我认为anamsc 和BuffaloBob 说的都是正确的。 有时候有些人就当是一般的问候语how are you来回答。 但这个更深层的意思是问 "你在做什么？你最近怎么了，或者发生什么事" 你可以看看老友记里面有几个回答的方式。就知道了。

If somebody asks you "What's going on?" they are basically asking you "What are you doing?" or "What's happened in your life recently?". A similar expression we sometimes use is "What's Up?" or "What's new?" which are other ways of asking "What are you doing?" or "What is new in your life?".