BioWare's hidden page did turn out to be somewhat misleading, as the demo will in fact be released on February 22--not February 23, as the hidden page stated.
The demo starts off during the game's prologue before jumping to the new location of Kirkwall. As a bonus for completing the demo, you'll unlock a special weapon to use in the full version of the game, the blade Hayder's Razor. That's another one to add to the colossal pile of items players can already obtain before even loading the full game.
The Dragon Age 2 demo will be available for PC, Xbox 360 and PlayStation 3 on February 22. The full game is slated to launch on March 8, hitting the same platforms.