Good links, though Lebovitz (who I read and usually like a lot) had bad info on two points at the time it was written:

1. I've been in Paris since Jan 17, 2008 amd they were still selling Carte Orange. They may well have stopped now with the introduction of the Decouverte.

2. Sales of the weekly Carte Orange were not just on Sundays, Mondays and Tuesdays. You could buy the next week's pass as early as Friday and as late as Wednesday-I did both. Anyone know the real restrictions on sale dates for the Decouverte? There may not be any since it's electronic, rather than having coupons with the date on each one.