I joke of course, because Unreal Tournament 3 had the option to cook mods for the PlayStation 3. Modding console games isn't a mainstream practice, though, especially since the hardware vendors tend to be afraid of what users will put into their systems. Third-party content is pushed into the realm of hacked consoles or emulators.
In this case, SEGA, over a decade after they made their last console, has decided to allow Steam Workshop with their SEGA Mega Drive Classics Hub (which corresponds to the SEGA Genesis for North Americans). The purpose of this is “allowing you to share modified versions of your favourite retro SEGA titles”. Sonic the Hedgehog is featured prominently in the promotional video, but will not be available at launch. The list is fairly long, however, and includes games like Ecco the Dolphin, Vectorman, Golden Axe, and so forth.
I am a big fan of long-term support, especially for user-created content. Video games are an excellent way for people to express themselves, be it with ridiculous and cruel Sonic levels, or with something more abstract. Regardless of their reasons, I'm glad that SEGA is giving a part of their platform to their fans (and society as a whole).