The headline at the Los Angeles Times blog says it all:

"Obama Quits Senate after 46 months - 21 of them seeking another job

Hmmm, a little math is in order: 46 months in the Senate minus 21 months formally running for president equals 25 months, or a little over two years,  of actually serving in the Senate where, frankly, he didn't do much.  That, plus time spent serving as an Illinois state legislator where he mostly voted present, a part time gig as a law instructor and his signature stint as a community organizer comprise the experience he brings to the presidency.  The presidency of the United States of America that is, not student council president (maybe the latter is more complex).

But serving in the Senate was important to Obama according to the statement he released prior to his formal coming resignation on Sunday. 

"It has been one of the highest honors and privileges of my life to have served the people of Illinois in the United States Senate. In a state that represents the crossroads of a nation, I have met so many men and women who've taken different journeys, but hold common hopes for their children's future. 

"It is these Illinois families and their stories that will stay with me as I leave the United States Senate and begin the hard task of fulfilling the simple hopes and common dreams of all Americans as our nation's next President."   November 13, 2008.