The Disney Dining Plan brochure can be downloaded from the WDW website.
This includes a listing of all restaurants that are on the Dining Plan,
as well as additional information about number of credits used, counter
service vs. table service, etc.
To download the brochure, click
HERE, then click on the Disney Dining Plan card, then click on "Download Disney Dining Plan PDF."
As you can see from the brochure, some, but not all, of the restaurants at Downtown Disney accept the Dining Plan. Among those that do accept the Plan are: Wolfgang Puck, Raglan Road, Cap'n Jacks, and Planet Hollywood.
Happy eating!