If you're one to believe a certain Major Nelson, then there is currently a Turok demo available on Xbox Live Marketplace right damn now. Alas, it seems as though Major's many spies (birds, beasts) are misinformed, as said demo is nowhere to be found. Nope, nothing. We continue to stare at the screen, hoping desperately that the demo will make itself known to us. We've uttered all the elvish passwords we know, but so far our efforts have been fruitless. With any luck, we'll stumble upon the answer soon.
Update: Major Nelson has updated the availability for the game. The demo is available in the following regions: Australia, Austria, Belgium, Denmark, Finland, France, Germany, Hong Kong, India, Ireland, Italy, Netherlands, New Zealand, Norway, Portugal, Singapore, Spain, Sweden, Switzerland, Taiwan and United Kingdom