It's here! Archie Comics' 12-issue "Worlds Collide" arc that mashes together the Sonic and Mega Man universes has begun, and there is much rejoicing. I received the first issue (Mega Man #24) in the mail just last week, and non-subscribers can spin dash into bookstores and snag their own copies today.
IGN has uploaded a limited animation trailer of the long-awaited partnership -- when I say "limited," think along the lines of motion comics. You'll catch glimpses of various panels from the first issue as well as sneak peeks at upcoming events. You'll also be introduced to the Roboticized Masters and Chaos Devil, the unholy unions of Wily and Eggman tech. But the biggest tease of all is the reveal of Mega Man's all new "Super" transformation: a golden variant of his Rush Adapter armor from Mega Man 7.
For those who haven't picked up the first issue yet, it spends the bulk of its pages establishing the ground rules. Essentially, Wily and Eggman have used the power of a Chaos Emerald to perform a "soft reset" of both universes, thereby separating "Worlds Collide" from the comics' past events while still remaining canon. This means you can safely hop on board without ever having read a single issue of either Sonic or Mega Man. A bit of a cop out, sure, but it's all for the sake of attracting a wider audience.