You never know whether this person suddenly lost their Internet connection or was called away for an emergency, or purposely disconnected because they were losing. I would lean towards not doing anything, personally.
Chess.com has recently put in place a system where if someone keeps disconnecting in losing positions, they will be unable to challenge people until they play some games properly. This kicks in automatically, so I don't think there's a need to report them.
@DavidMertz1: Good point! True, I don't know if he disconnected on purpose, but because of the way the game went, I knew that it was highly likely, hence my question. I will let the matter drop. Thanks!
whirlwind2011
This page may help 
http://support.chess.com/Knowledgebase/Article/View/171/13/fair-play-policy
@kohai: Yes, I do recall seeing that policy now. Thanks for the reminder!
You got the win, right? So what else is needed? Happened to me many times. Very annoying, I grant you. I didn't know there was a policy covering it.
The fact is that a disconnection during a Blitz game is not as long as one during a 30 min game (or longer). You can easily wait a couple of minutes, but it's harder to wait a half an hour in front of a monitor untill the adjudication will come.
I just played a game on Live Chess that my opponent abandoned. I am not necessarily so upset about that, but I was wondering, what is the proper action to take? Is it my responsibility to report him/her for abuse, or should I just let it go? Like I said, I am willing to forget about it, but first I just wanted to make sure that I wasn't expected to take some sort of action.