Basically it lightens up the shift feel. A lot of people love it, a small number think it makes the shifter too notchy. Personally, I like the way my car is shifting now, so I won't mess with success (and I have an STS coming before the end of the month).
There is also a huge threat started by WD40 very recently.
"Do or do not... there is no try." - Jedi Master Yoda