Thanks to an accidental Wal-Mart.com listing, we now have details on the first Scooby-Doo LEGO sets announced! LEGO will be creating figures for a new "LEGO Dimensions" game. You can send the figures "in the game" by putting them into a special portal.
Not much else is known now, except a possible September 29th release date in the US and UK. (it was listed on the Walmart.com listing, but Wal-Mart removed it because they weren't supposed to announce it yet). More info to come!
Here's another picture of the figures: