Although exact details of Mustaine's involvement haven't been revealed (will the conductor guide him with devil-horn hands instead of a baton?), AntiMusic reports he's a featured soloist during a program that includes pieces from Wagner, Vivaldi and Dvorak. The Wagner composition in question is one you know, even if you think you don't: "Ride of the Valkyries," which was featured in Apocalypse Now and spoofed by countless cartoons and TV commercials over the years.
Mustaine's intricate, lightning-fast guitar work seems an especially good fit for Wagner, since both share a penchant for bombastic, take-no-prisoners compositions. Plus, they're both crazy! Mustaine hates our president with a passion that goes beyond logic and Wagner was a rumored anti-Semite. Mustaine's mother was Jewish, though, so he probably doesn't share Wagner's idiocy on that point.
Regardless, it should be a fascinating ticket once they hammer out the details. And even though it's an obvious choice, it would be pretty damn awesome to see Mustaine do Megadeth's classic "Symphony of Destruction" backed by a real-life symphony. Make that happen, guys.