Disney's website lumps the Premium and Platinum Package Plans in with the regular dining plans, which it really shouldn't do. When the website says Portobello, Fultons, T-Rex or the Rainforest Cafe accept the dining plan, they mean premium or platinum, not the regular or deluxe Disney Dining Plans.
So you really can't trust the website to give you accurate information. In fact, it's also listed a couple of restaurants (such as La Hacienda) as NOT accepting the dining plan when they do. The way to check is to look at the Disney-published 2011 dining plan brochure (there is a link to it in a sticky thread on the Dining Plan board). If it's not on that brochure, it doesn't accept the dining plan. (Make sure you are looking at the brochure that has a printing date at the bottom - in small print - of 121010. Any 2011 DDP brochure dated earlier than that is not complete.)