I haven't seen any changes to the five, but they did give the $20 a makeover (more in an effort to thwart counterfeiters than in an effort to look different).
Andrew Jackson has been freed from his oval frame, an eagle has been added to the background of the front. The colours are now a gradient across the front going from blueish green, to creamy yellow-pink, and back again. Also tiny golden "20"s have been sprinkled across the background of the back.
New:
http://images.usatoday.com/money/_photo ... l-pop2.jpg
Old:
http://www.arcytech.org/java/money/images/20_bill.jpg