The twenty-dollar bill is set for a change this spring, and a new color will be unveiled on March 27th. The new design is known as NexGen, and the new twenties will likely come into circulation in the fall, with redesigned fifty and hundred-dollar bills to follow within eighteen months.
A PBS article from last year called Secrets of Making Money describes some of the security features that will be retained in the new design.
The Associated Press talked with both the chief portrait engraver and the head of the Bureau of Printing and Engraving on the change, last December. Engraver Thomas Hipschen mentioned how Duke Ellington might look nice on one of the redesigned bills. Something to think about.