This is about two years behind schedule, so I'll believe it when I actually see it.

The final rollout of the revamped family of colón bills will take place August 27. The redesigned 1,000 and 2,000 bills have been out for some time, and the brand new denomination of 20,000 was also introduced about a year ago. (I've lost track of time on this.) Still to come at the end of this month are the redesigned 5,000 and 10,000 notes and, for the first time, a 50,000 note. At the current exchange rate, 50,000 colones = about $100.

The old 1,000 and 2,000 bills are long gone. The old 5,000 and 10,000 bills will be valid through the end of the year, in case you have any left over from previous trips. After that, they need to be exchanged at any bank for new bills. After May 1, 2013, they can be exchanged only at the Central Bank.

The bills are quite attractive. A slideshow from the Central bank's website:

Nueva familia de billetes

The front shows figures important in Costa Rica's history. The reverse shows the country's different ecosystems. Each bill is the same width, but different lengths.