A programmer who was tinkering with Skylanders: Spyro's Adventure was stopped in his tracks by a cease & desist letter from Activision. Brandon Wilson discovered the security protocol that the figurines use to interact with the computer, and posted a few vague details on his blog before receiving the legal notice.
Wilson's personal site (via The Escapist) mentions documenting the Skylanders protocol and encryption method, and that he planned to emulate the portal using graphing calculators. It wasn't long before followed up with another note: "And here come the Activision lawyers! Suffice it to say, I've been shut down, so uh... nevermind."
He notes in his response that he is not collaborating with other hackers or intending to distribute the file publicly. "This research project was for my own personal knowledge and to satisfy my own curiosity as to how the game interacts with its USB peripheral," he wrote. "I have expressed no desire to release to the public tools that circumvent Skylanders' access control measures, and I continue to express no desire toward that end. I do not and did not have any intention to harm Activision or cause harm to its products or investments.
"I re-iterate that I have and do intend to comply with your request to cease any and all research and development into how the game Skylanders: Spyro's Adventure works," he continues. "Any and all publicly accessible documentation and/or source code has been removed to the best of my knowledge and ability."
Wilson seems to have handled the situation reasonably, but as The Escapist notes, Activision's letter referenced leaks that weren't his. He only had a zip file from a data dump that he didn't release to the public. It's necessary for Activision to protect its legal interests, especially when it comes to a game like Skylanders that relies on purchasing extra figurines to support its business model. Sometimes that means bearing down on fairly harmless hobbyists.