The quote below from NaturalNews.com is the best explanation I've seen about what the FDA actually did with regard to Stevia last week. They did not give a blanket approval to all use of stevia. Rather, they notified certain companies they had no objection to their stevia products being used as a sweetener, including in food and drink products. It is a big step forward for stevia in the U.S, but it seems the approval process is not yet complete.
FDA Approves Stevia, Ends the Era of Oppression of this Herbal Sweetener - UPDATE 1: "Technically, the FDA has only issued letters of 'no objection' regarding companies' self-affirmation of GRAS approval for stevia. In other words, the FDA hasn't technically granted approval to stevia but has affirmed it will not object to companies using it in foods and beverages. This puts stevia in a 'grey zone' where the FDA could potentially target selected companies (small stevia producers) while ignoring other companies (Coca-Cola and Cargill, for example), even while they use essentially the same sweeteners."