Update: Geithner was sworn in shortly after 7:30 p.m. President Barack Obama attended the ceremony, Vice President Joe Biden Administered the oath of office.
The vote was 60-34. Geithner earlier cleared the Senate Finance Committee with an 18 to 5 vote; one of the dissenters, Mike Enzi, said that "in previous years, nominees who made less serious errors in their taxes than this nominee have been forced to withdraw."
The Obama administration backed Geithner despite his tax problems, however, and consensus formed in Washington that the country's economic problems were too significant for Geithner's "careless mistakes" to derail his nomination.
The 47-year-old is seen by many as the best candidate for the job, and there was concern that rejecting him would mean a delay in confirming a replacement that the country could not afford.
"The economic situation is so tense right now and I don't want see us go back to square one and wait several weeks or longer for the process to bring in a new treasury secretary," Republican Sen. Arlen Specter said today, according to the Associated Press, in explaining his support for Geithner.
Geithner will oversee the Internal Revenue Service and oversee President Obama's efforts to stimulate the economy. You can read more about his plans here.