But he's not coming alone. When the comics' Ultimate Spider-Man joins the animated Ultimate Spider-Man, it'll be as part of the third season, premiering August 31st and subtitled Web Warriors, where Spideys throughout the multiverse join forces.
The Spideys include Spider-Man Noir, Spider-Man 2099, Spider-Girl (who is Petra Parker in the cartoon, from a gender-swapped universe), the Spectacular Spider-Ham, and someone USA Today is calling Iron Spider, despite the fact that name is usually reserved for Spidey in his Tony Stark-designed red and yellow outfit, which Peter Parker has already worn on Ultimate Spider-Man on several occasions.
But whatever. Miles Morales will finally make his animated debut! It's probably too much to ask for that he'll stay on past the season, but hey, it's a start.