The GameCube and Wii emulator Dolphin will no longer come to Steam.
Now the team have cleared up the situation and are abandoning their efforts completely.
What actually happened was a legal back and forth.

Valves legal department had contacted Nintendo regarding the emulators Steam release.
A lawyer representing Nintendo asked Valve to prevent it.
Hence, the team is abandoning our efforts to release Dolphin on Steam.
They go on to say that only a small fraction of what we do involves circumvention.
Dolphin is still available to download on its own site.