The NYT looks at possibilities for the first Female President, assuming Senator Clinton does not become POTUS.
In my opinion, anybody over 65 is too old to be elected President. The candidate needs some experience - either in elected offices, or outside. Also, despite this year's events, Senators are less likely to be elected POTUS. With these criteria, let's look at the prospects:
65 or over in 2012/16:
Governor Kathleen Sibelius (D-KS) - I hope Senator Obama, as the Democratic nominee, picks her as running mate this year. If not, then she can run in 2012 if Senator McCain becomes POTUS. In 2016, she will be 65+.
Senator Kay Bailey Hutchinson (R-TX) - she will be 65+ very soon. Out.
LtGovernor Beverly Perdue (D-NC) - Running for Governor of NC. She will be 65 in 2012.
Senator Amy Klobuchar (D-MN) - Young, but Senator. Can't be ruled out, though.
Governor Sarah Palin (AK) - Young, Governor.
Governor Janet Napolitano (D-AZ) - term-limited after 2010. Less likely VP pick for Senator Obama this year.
Sarah Steelman (R-MO) - MO-Treasurer, running for Governor.
Lisa Madigan (D-IL) - IL-AG, could run for Governor.
Meg Whitman (R) - Ebay is very successful. She might run for Governor of California.
Condoleezza Rice (R) - US Secretary of State, tied to the Iraq war, but public memory is short.
Chelsea Clinton (D) - Not before 2020, has to get some life experience/get elected.
Carly Fiorina (R) - If she runs the country like she did HP... though that didn't stop the current POTUS!
Or someone else...?