They're not the theatrical versions, but rather how the movies appeared on LaserDisc in 1993 (right before the Special Editions).
There is ONE exception... the re-created 1977 Opening Crawl for the original "Star Wars." That has never been seen in an official release before (the rental only video tape from the 1980's had the real original crawl, but it was full frame only, not widescreen).
But... the versions coming out on DVD are supposed to be the original theatrical showings... just in Dolby 2.0 or something...
Despite the marketing hype, StarWars.com has reported them repeatedly as being the 1993 editions.
First off, the original Star Wars was in MONO in theaters. This was somewhat rare as stereo versions were created and Aunt Beru's lines redubbed. A six channel 70mm print of this and all three movies WAS available in select theaters. So some of us did see these films in six channel stereo (which would not be properly simulated by Dolby 2.0).
So when they say "original theatrical" read that as "on home video in 1993+new opening crawl for Star Wars").
When I say "reconstructed" I say that because presumably all the prints with the original crawl are too deteriorated to use. So, using a computer, they reconstructed it pretty much as it would have been, before "Episode IV: A New Hope" was added, Rebel was capitalized, and the words were re-ordered to prevent a sentence ending with a single word (that was in 1981, so all home releases for purchase had it, unless you bought a used copy of the first Star Wars rental tape being put up for sale).
Just to point out something, the posters aren't always to be "trusted" when it comes to what they portray in the movies. Some posters show Yoda as bright green. He really isn't, but more yellow/olive/light green (except in scenes where there's lots of contrast). The "super green" Yoda is a product of the prequels and reflects itself in the green tinted scenes of Yoda in the 2004 edition.
The lightsabers are notoriously off in the posters. Luke's saber is consistently blue in the ROTJ posters. In the "Revenge of the Jedi" poster, Luke's saber is actually RED and Vader's is blue (or purple, though that could be due to damage or a bad scan).
Posters are done in advance of the movie, so they are not always in step with the effects (Luke's saber changing from blue to green in ROTJ seems to be a late decision, it actually appears blue in the trailers).
It's also worth pointing out that Lucas did have CG ships added to the SE's and later, and in that process he could have introduced more colors if he wanted to (though I don't think he added any blue TIEs into ANH, I'd have noticed it). The recolor job through the 2004 editions was hokey, but it is possible to have one color model and just recolor it when the mood suites you. But if you want to know the "real" colors of the ships, watch the "theatrical versions" or the Special Editions, not the 2004 editions, which notoriously screw up colors.