Usually any news about Left 4 Dead 3 is nothing more than rumours, however a leak today has given fans of the series a look into what they could expect when the game gets released. The leak was seen on neoGaf and shows screen shots of Left 4 Dead 2 Plantation map which has been rendered using the Source 2 engine, which will be behind Left 4 Dead 3. At the moment it is not known if the Plantation map is going to play a part in Left 4 Dead 3 or it could be that Valve are using it as a demo.
The slides in the screen shot show us that Source 2.0 will have tools that have been redesigned along with workflow that is redesigned. There is also a powerful GUI front end for content authoring. It was said that the engine could be extended with pre-game assets and there is a browser for finding, managing and editing assets.
Back in August we saw two different leaks that said the game was under development using the Source 2 engine and had been for around a year. Gabe Newell did confirm that they were working on the Source 2 engine and that there would be a game rolled out alongside it.