Starting March 2, 2009, the price to send a Prioritaire letter (up to 20 g) within France & the DOM-TOMs will be 56 centimes, a 1 centime increase from last year. The cheaper Ecopli price will be 51 centimes, also a 1 centime increase.
The price to send a letter within the European Union & Switzerland will be 70 centimes, a 5 centime increase from last year. [Apparently this also includes Liechtenstein, San Marino and the Vatican, which are not in the EU... But definitely not Norway, Iceland, or Andorra, which are also not in the EU.]
For the rest of the world, however, the price remains at 85 centimes.
La Poste’s website has pdf files you can download for all the new prices, for mail originating from France Métropolitaine and the DOM-TOMs.