No, they use a custom engine (Ron Gilbert's pre-existing engine with the Squirrel language for scripting, augmented with custom sugar around coroutines to more or less emulate the way SCUMM did threading).
Well, their lead tester is Robert Megone who used to work on ScummVM (and for Revolution Software), but that's not really using ScummVM.
ScummVM is used by Disney (who bought the copyright of most of Georges Lucas' stuff) for their GOG re-releases (10 years after LucasArts sent out the lawyers to try to shut down the project), and by others for non-Scumm games as well.
Also, the guy who wrote the point and click interface for Grim Fandango on ResidualVM was hired by DoubleFine as a consultant so that they could adapt his code for the remastered version.
That's all the ScummVM-related trivia I could remember from the top of my head.
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