Does any professional golfer use AND describe in a publication or web
site (SPECIFY WHERE), a TRUE BASEBALL GRIP, that is, holding the club
just
like a basball bat, with all ten fingers on the shaft and with both
thumbs AROUND the shaft? I DO NOT MEAN the commonly-used and
-described "10-finger grip," where the thumbs are ALONG the shaft,
which is (incorrectly) referred to as a "baseball grip."

From GolfWeb - Ask Annika Sorenstam:
http://services.golfweb.com/library/sorenstam/iqa/9708.html
"Q. Dear Annika, 

I have always used the interlocking grip but have been experimenting
with the overlapping and baseball grips. The baseball grip feels more
comfortable to me and has increased my shot distance. My question is
whether the baseball grip is used by any professionals or is it really
too unorthodox for the serious golfer?

Maria
St. Louis, MO 

A. I really don't know. I can't think of anyone using this grip. I
would recommend talking to your local professional but if it works-go
with it. "

There's a Canadian pro golfer, Moe Norman, who teaches a system he
calls "Natural Golf," which begins with the baseball grip (or
something very like it).
You can read about it on his website, http://www.naturalgolf.com/,
which also sells instruction materials (mostly videotapes, I believe)
and equipment.