I'm looking for a single publication or a single
web site that lists all of the governors -- past
and present -- of all 50 U.S. states, and for each
governor his or her dates in office and party
affiliation.

Dear vortex,

I have found a comprehensive list containing the governors for all
states of the USA from the country's beginnings up to the present day.
However, because of its really enormous length the list is split into
seven seperate websites, but all belonging together. Using a word
processor and the copy-and-paste function, it should be very easy to
create a complete state governor list, which would of course fill
quite a few pages.

Links:

Rulers: Countries U - U.S. States A-D
http://www.rulers.org/usstat1.html

Rulers: Countries U - U.S. States F-K
http://www.rulers.org/usstat2.html

Rulers: Countries U - U.S. States L-M
http://www.rulers.org/usstat3.html

Rulers: Countries U - U.S. States N
http://www.rulers.org/usstat4.html

Rulers: Countries U - U.S. States O-R
http://www.rulers.org/usstat5.html

Rulers: Countries U - U.S. States S-U
http://www.rulers.org/usstat6.html

Rulers: Countries U - U.S. States V-W
http://www.rulers.org/usstat7.html

Source:

Rulers - A database of heads of state and heads of government of all
countries and territories, by B. Schemmel, 2002
http://www.rulers.org/

Hope this is what you were looking for!
Regards,
Scriptor

Excellent answer: dead on and delivered within an hour.