The guys over at Trekcore.com
have posted the Season 4-Trailer:
The switch to digital photography in season 4 is really apparent, I think. Even in the Trailer the colors pop of the screen compared to the first two seasons on Blu-Ray. Everything seems to be a bit sharper as well. On the other hand the show also has kind of a certain videolook now that was really apparent in these early digtial cameras.