From what I can gather, a while ago there was this huge "Get it off the yeast!" movement that encouraged brewers to rack to a secondary when the primary stages of fermentation were done. Personally, I've never used a secondary because I think the benefits are minimal compared to the risk of oxidation/infection.
As a generality, modern brewers are abandoning the secondary as leaving it on "dead yeast" really doesn't act as a detriment to the flavor of the finished product. With the size of the batches most of us brew and the newer, more specialized, yeast strains we use; I don't think there is enough yeast die off to worry about that sort of thing.
If you subscribe to the secondary theory then by all means go for it. It will free up a carboy for you and if you wanted to rack on top of some kind of flavoring (i.e. wood, fruit, ect.) this would do the trick. Personally, I don't have a use for it.