Original von "Optional"
Stargate Universe is taking a page out of Battlestar Galactica. In terms of being darker, and gritty, and almost completely character driven compared to its 2 predecessors.
An off world base finds a 9th chevron, and they are forced to make an emergency evacuation of the base (not sure why) and travel to this ninth chevron address.
It takes them to a REALLY old Ancient starship called the Destiny, which was part of an experiment the Ancients were doing to seed all the galaxies with Stargates.
The Destiny is stuck on its course, and will only stop at a planet for a certain amount of time. If the team decides to explore this planet they must get back to the Destiny on time or they will be left there forever.
As I said, SG:U will be focused on character drama, and less on aliens with plastic glued to their foreheads. You can expect major plot twists, people stabbing each other in the back (figuratively), and all that great character stuff.
BTW, Richard Dean Anderson won't be 'staring' so much as guest staring. SGU will have earth stories as well. Think of it like LOST, it'll have flashbacks to characters back on earth before they were in the Stargate program and such.