With the speculation that Napolitano may have one foot out the door, the reality of Jan Brewer becoming Governor is starting set in. Seeing Red has an excellent breakdown of another time that this happened when Castro left to become ambassador.
The Obama win/Napolitano departure is a mixed bag for both Republicans and Democrats. For Republicans, there would be a fiscal conservative running the show and getting the budget under control. On the other hand, it would mean that McCain lost and there is a new team in Washington finding different ways to spend money. For the Democrats, it would be a big win to have a Democrat return to the White House, but then they would have to deal with Brewer locally which wouldn't be in their favor. Which is better to be happy locally or nationally?
It is also interesting to note, that since Castro took over in 1975, Arizona has not had a Governor that has entered and left the office under "normal" circumstances:
Raul Castro January 6, 1975 to October 20, 1977
(Left to become ambassador)
Wesley Bolin October 20, 1977 to March 4, 1978
(Took over for Castro, Died of Heart Attack)
Bruce Babbitt March 4, 1978 to January 5, 1987
(Took over for Bolin)
Evan Mecham January 5, 1987 to April 4, 1988
(Removed from Office)
Rose Mofford April 4, 1988 to March 6, 1991
(Took over for Mecham)
Fife Symington March 6, 1991 to September 8, 1997
(Forced to Resign)
Jane Dee Hull September 8, 1997 to January 6, 2003
(Took over for Symington)
Janet Napolitano January 6, 2003 to ???
If Napolitano leaves, the cycle will continue.