Slav defense 1.d4 d5 2.c4 c6 3.Nc3 e6 4. e4

UPDATE: Just for clarification, I am wondering if there are any major traps or similar, and if e4 is a good way to break up a center structure, if it will be extremely difficult to play, etc.  I rarely play openings with the king's pawn.

This is the well known Marshall gambit ........ and isnt it black to move in the diagram ?

If this is an ongoing online game on this site then you can consult books, databases and other such static resurces but I think asking other peoples take on things is something you should not do.

Admitely this distinction might sometimes be bit problematic  in the opening stage. Just imagine that by coincidence you would have asked about this opening in the forums just the day before game begun. Then in all probability the conversation in that thread would still be going on when the game reaches this position. So if I'm wrong here then someone please correct me.

Yes, it is black to move.  I have not yet made the e4 move and have been unable to find detailed information on it online.  It seems like it might be a good way to break up his center though, so that was why I was asking.

Indeed this is the Marshall gambit, which seems to be a good way for white to play sharp and avoid the dreaded noteboom variation. I don't know much about it besides the fact that it can get sharp, and that many black players like to avoid it, although theoretically black should be OK. I would recommend learning the theory before you play it though, so that you get good compensation for your pawn, and so that you know how to play the sharp positions that arise.

Play 3. ...cxd4 and you can let him play e4 and you can win ^^

2300 that was almost a decade and a half ago.

Thanks!