SevenCubed - 10:49 pm on Oct 30, 2012 (gmt 0)
I say unfortunately because it's baaaad and you should never do it.
I've been thinking it over and can't come up with any real good reason why it would be baaaaad. I haven't used it myself because I have never had a need for it but I wouldn't hesitate if I saw a valid purpose.
I just see it as cutting a hole in the end of a shoebox (the div) and pushing an uninflated balloon (linkwholediv class) into that hole and inflating it to fill the volume of the div.