No, when I've done it they stop when they hit the ledge unfortunately,

http://www.youtube.com/watch?v=rOlNKLqaxBg&feature=related

Here's a video I found of it with wolf. This could be useful if you do it near a ledge since the opponent stops sliding when it gets to a ledge so if you're near the opponent you could attack them.

The thing that could make it useful is that they are sleeping when they come out of it. So at higher percents it might be able to be used to set up for a kill. The timing would have to be really precise though.