Looks like the RIFA cap blew.
When they do blow, they make a big, stinky mess, but they don't generally cause any major damage from what I've read (I guess I've been lucky, for I've yet to have one blow in any of my machines, so I actually don't have any first-hand experience so far). I've also read that machines can usually continue to work without them, so once you clean it up, if you're brave, you can carefully try powering it on to see if everything else works as it should (somebody please correct me if I'm wrong!).
That mess looks pretty extensive though, so at a minimum before you do anything else, you should clean it up, remove the blown RIFA remnants, and then visually check other components in the area to make sure nothing else got fried. A general recap probably wouldn't hurt, either. This includes installing a RIFA-equivalent; as noted above, the machine would likely work without one, but I think it's a good idea to install a new one anyway for reasons I don't recall at the moment.
c