It looks like the special surprise is out the bag. User Bonehedge at the official Bethesda forums discovered a Steam Content Description record submitted on January 31st that reveals a “HighResPack” in testing for the “skyrim” application.
Whether the new textures will simply be uncompressed textures that shipped with the game remains to be seen but even they should be a marked improvement over the ones that were shipped. The real question is whether it will be as good, or even better, than the mods currently released.
Regardless, it’s nice to see a developer release a higher quality texture pack for the PC editions, which can often handle obscenely large texture files relative to consoles. I can’t even remember the last time a company did something like this. The last one I remember for sure was Half-Life.