Straight to the top of the all-time IMDB top-250, will certainly become a cult classic for the ages, ground-breaking sci-fi. Certainly made for absolutely gripping viewing with a combination of great visuals/action and intricate plot.

OK, here goes my theory on the meaning of it all:

The 'Inception' is real, it is the theme of the movie itself, the idea that what we perceive as reality may in fact be a multi-layered dream, this idea was implanted by Nolan (the directer) in the sub-conscious minds of the audience (you and me, the movie-goers), we think the ideas are are own, but they were implanted by Nolan (all the theories, forum discussions, twitter, movie reviews etc), it is WE who have been played and the heist has succeeded for real! The movie itself is the dream, the characters are the projections of the audience (you and me, the movie-goers), the dream ends when the movie ends, and only we (you and me, the movie-goers) by continuing to participate in the shared dream (discussion on forums etc) can decide how the story is supposed to end. You see, the reality you see around you right now (the 'real-world' may not be the ultimate reality.

You gotta REALLY think outside the box to get this

What's interesting about this is that Nolan has deployed ALL of the classic plot 'twist' devices at once, see Wikipedia link below.

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Anagnorisis: Characters frequently experience sudden shifts in their identities caused by what they discover when exploring their own sub-conscious.

Flashback: The key flash-backs are the scenes with Cobb's wife and children.

Unreliable narrator: We know Cobb is psychologically unstable and has issues, further we are entering his dreams.

Peripeteia: Blurring of dreams/reality causes sudden shifts in fortune.

Deus ex machina: The dream-technology itself makes anything possible, e.g., improbable escapes from death (when I die I will wake up).

Poetic justice: The notion of 'limbo', Cobb's guilt and exposure to his own subconscious.

Chekhov's gun: The totem and its ultimate significance.

Red herring: Many confusing elements in the film allow for much confusion and conflicting theories (e.g., dream physics, mazes, collapsing buildings, frenetic action scenes).

Cliffhanger: Obviously the ending is a cliffhanger, emphasizing the idea that ultimately we don't know what is a dream and what is reality.

In medias res: It is emphasized that characters enter dreams in the middle of a story, with no idea how they got there.

Nonlinear, Reverse chronology: The three-level dream sructure with different rates of time flow allow Nolan to play with time.

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