It's always strange to me when a studio has the means to provide not only a poster, but a trailer for a film that still has no official synopsis. The notion holds true for Inception, which has received its first official poster just today.
Inception Poster
"Inception is a contemporary sci-fi action film set within the architecture of the mind." That's pretty much all we know. The trailer doesn't really help much, but it does prove that the film will be trippy as heck.
The poster, which shows DiCaprio getting his shoes wet, provides a bit more info with the tagline: Your mind is the scene of the crime. Okay, now I get it! Well, er, not really. Check out the poster below.