The new 100 dollar bill is coming out in February 10, 2011.
You will have until Feb. 10 to spend your existing pile of 100's -- though they will still work.
The currency changes started in 1996 with the $100 bill, followed by a new $20 bill in 2003. The $50 bill got an overhaul in 2004, and the $10 was redesigned in 2006. The $5 bill was upgraded in 2008.
$100 bills are the most common use of American currency by foreigners. Two-thirds of all $100 bills are in foreign pockets. Therefore, international counterfeiters feel they can get away with bigger sums of fake cash in the far reaches of Europe, Africa, and Asia – not to mention being far from the spotlights of law enforcement.
From October 2007 to August 2008, approximately 61 percent of the counterfeit money passed domestically was produced using digital means. It's a big problem for retailers where its all about catching the funny money at the point of sale.
The U.S. Department of the Treasury, the Federal Reserve Board, and the United States Secret Service designed the new bill to keep American money safe from illegal manufacture. As the highest unit of paper currency in the U.S., the $100 bill correspondingly carries the highest level of security features.