Not only is the recurring President on that show also played the President in the movie, but one of Bane's Mercs was played by another Stargate actor as well.
I saw that too. I've known about Chris Judge being in the film for awhile. He interviewed with Gateworld last week:
http://www.gateworld.net/news/2012/07/chris-judge-slightly-breaks-his-dark-knight-silence/
From this, I would guess that he was originally cast to be Bane's right-hand man, Barsad, but ended up having a lesser role due to his height - either that or his character was going to be around Bane more frequently and had to be diminished when it became obvious he was more physically imposing than Bane.
I knew about Judge, but didn't know William Devane was in it. When he popped up, I instantly asked the same question you did in this thread. He's often played cabinet members and has played the President of the United States three times now. The first time was playing JFK back in the 1970s in a TV movie about the Cuban Missile Crisis. I remember watching that one in school.
I'm sure Nolan was aware of his role in SG-1 and may have liked how he played it.
Looking at it, I wonder if they had originally thought they could use some cinema tricks to not make Judge seem so imposing in comparison. I also wonder if that Barsad character may have originally been a more intimidating right-hand man, maybe Ubu. I could see Chris Judge playing Ubu, but if they couldn't make it so Bane would be more intimidating and clearly in charge on screen then they would have dropped it quickly. Barsad seemed more like a sycophant who was incredibly loyal, but not strong in his own right.
Although I do see Bane as owing a bit to Ubu, but making Ubu the bad guy would have been a dead give away to who was really pulling the strings.