I've seen this tag and used it myself, but I'm inclined to say that it has no effect anymore. From what I've gathered in my own research, and confirmed herein, Inktomi once had a default behavior of "index,nofollow" whereas all other important engines had as a default behavior "index,follow."
My question - has Yahoo! continued in this manner, placing any emphasis on the tag? Or perhaps MSN?
I've seen no evidence to suggest this, but wanted to know if anyone could shed any more light on the issue.
~Canton