Inception is the best brains-in-vats movie out there. The bastard child of the Matrix and Dark City, Inception contains three plots each neatly wrapped around the others like a 6 sided mobius strip. First you have the action movie with strong elements of Shadowrun: kicking ass, taking information and running like hell. Then you have a quasi-romantic thing going on between DiCaprio's character, Cobb, and Page's character, Ariadne. Finally, there is the most important plot, that between Cobb and his own demons.
That is all I can say without giving away the plot completely. Suffice it to say, instead, that if you're looking for the best philosophy-action flick to come out in the past ten years you'll just have to get your butt to a theater and see it.
One last thing: go to the IMAX version. Because there's something about having your inner ear cry out for mercy when your watching a zero-g fight sequence that is always wonderful.