Quoting a bit more from the Nauseated page:
Nauseated creatures are unable to attack, cast spells, concentrate on spells, or do anything else requiring attention. The only action such a character can take is a single move action per turn
It seens to me that "anything" includes special abilities, such as as Shift. The RAW is pretty clear - if it is a move action that is not a spell, a attack, or anything that requires attention, you can do it while nauseated. You also can do only one of such actions per turn. Otherwise, you can't take that action.
So, no, you can't shift away. Your wizard probably will become food for some nasty DM critter pretty soon.
But... How about free actions? Can I drop something I'm holding, or maybe speak something?
Pure-RAW, no, you can't. The rules are pretty clear that you can only do a single move action per turn. However, I would rule that, if the Free Action don't need attentiveness, then you can do it without problems. You wouldn't be able to load a bow, for example, but it would be okay to drop a bow or other stuff you would be carrying.