Here is what - despite the writeups below - I consider the definitive article on the subject. I hope the original author, whom I haven't attempted to contact, doesn't object to this redistribution in a different medium.

From: (David Fergemann)
Newsgroups: harvard.general
Subject: Re: Power Putty: Info Wanted
Date: Jan, 1996 (Jonathan Liu) wrote:

> Cindy Alvarez wrote:
> :       "If an infinite number of monkeys typed at an infinite number
> :       of computers for an infinite length of time, they'd produce
> :       a paper which would get a B+ at Harvard."  -me
> I'm looking for an infinite number of monkeys and an infinite number of
> computers to type a paper for me.  Anyone know where I can find one?
One isn't going to do you any good.  The "infinite number" part was
important.  I've never believed the "infinite number of monkeys" idea
anyway.  If you said instead, "an infinite number of truly-random
character generators running on an infinite number of computers for an
infinite length of time," I'd believe it.
(Your typical pseudorandom function won't work; it repeats after a few
billion numbers or so).  The monkeys won't work for a number of reasons.

1) Monkeys will get bored, and won't type one character at a time.
Instead, you'll get stuff like:

X-IO432, .CXZX
 CZV ;ASskjzx c
X C. /ZX-=1
'C/XC0-WQ  \WE
?VC VB45A432we
?D;[2e   \[]c?x ;mpioqw\4352?GH';l[bvx-=trw123?!
';\]zx[  awre 3241;1-=sd?>Fg;lk230-=AS
';ZX C.,/WEQ[]
?:vzc;odssa\q  [\]vc,.mldf;':i690-hgfdc

(I typed that with my knuckles).

2) As you can see in the above example, knuckle-typing leads to serious
problems, including:
   a) high frequency of the semi-colon and other punctuation
   b) Rather than single capital letters followed by strings of lower case
letters, you wind up with strings of capital letters, due to the caps-lock
   c) Extremely redundant.  In particular, notice the digraph frequencies
(count the number of times you see "zx", "jk", "23" and "kl".  Notice also
how frequently a line begins with ' " ? or / due to their proximity to the
return key.)
   d) A typical paper includes only one carriage return per paragraph.  It
looks like I'm averaging about one per 15 letters in the above.

3) Various other problems:
   a) Monkeys don't know how to adjust fonts and margins to make the paper
fit into the right number of pages.
   b) Monkeys might have a tendency to throw feces at the computer.
   c) The sun is scheduled to burn out within a few billion years, which
will put an end to the monkey typists.
   d) Your paper is probably due before then anyway.

Dave Fergemann