If you know your Floyd you also know of The Publius Enigma.

The Enigma began on June 11,1994 when someone 
 using the name "Publius" posted a message to the Floyd newsgroup.

Date: Saturday, June 11th, 1994
Subject: >>>>>>>>T  H  E   M  E  S  S  A  G  E<<<<<<<< 
My friends, 
You have heard the message Pink Floyd has delivered,
but have you listened? 
Perhaps I can be your guide, but I will not solve the enigma for you. 
All of you must open your minds and communicate with each other,
as this is the only way the answers can be revealed. 
I may help you, but only if obstacles arise. 
Listen. 
Read. 
Think. 
Communicate. 
If I don't promise you the answers would you go.
Publius 

And ended on April 5,1997 with this last message.

Date: April 5th, 1997
Subject: >>>>>>>>>ENIGMA<<<<<<<<<

Many months ago we embarked upon a magical journey. Although most
of you displayed truSt at the start---only a haNdful remained faithful.
So much has been revealed on thIs newsgroup as to the true nature
of modern man (and Woman). Disappointments are heavy upon my hEart.
I believe one of you has discovered the truth---and has placed the answer
here on this nEwsgroup. I now call for an end to this eniGma.
It appears that only one has been foCused on my first message so long ago. 
Listen
Read
Think
Communicate 
The disbelief on this forum forces me to reveal details in another manner
that
will be undisputed. This will be forthcoMing. The prize received will be
unique
as promised. It will be the decision of the winner to discuss it with the
rest. 
IT IS FINISHED 

During these few years proof of "Publius' " identity was demanded from the fans posting in the newsgroup.
The Proof was unmistakable. 

During a "Division Bell" concert in N.J. "Publius Enigma" 
 appeared scrolling through the light show.
Two days later ,during an Earls Court concert "Enigma" appeared 
on "Mr. Screen" while the song "ABITWII" was performed.


Publius posted this to the newsgroup ....

You need only look at the Circle in The Wall-
the Enigma has been announced worldwide.

The Enigma was closely followed for several years ,

 with clues being offered by Publius and Newsgroupers having lengthy discussions and arguments over the subject.

A "singular prize" was either never found or was not posted by the winner (last message).  


The Enigma is still mentioned on the Floyd newsgroups 
 (though prepare to be flamed if posting)
 and there are some very intensive websities about the subject.


The best I have seen (and the basis for this page) is :   
The Enigma