Does Skyrim work without Steam?
I can confirm that the main executable is not tied to Steam. Launching it directly start the game without going trough the "Loading game" steam window, and you can't access the steam community if you started it this way.
This was surely done to enhance compatibility with outside tools like Wrye bash or OBSE for oblivion. With Oblivion on steam, you can't launch the game trough an external launcher without going trough the vanilla launcher that steam launches.
Apparently, it was an oversight from either Bethesda or Valve, and was fixed in the first patch. (source)