I'm guessing the original plan may have been for it to take up it's original slot once the new Torchwood series finishes (in 13 weeks), but now that S2 has been held up in the states due to the writers strike, it may now end up being a bit later than that.
Series 2 has not been held up in the states. It was cut down to only 13 episodes and they have all been shown in the US. I downloaded them and have watched already, having watched series 1 on sci fi I was already waiting for series 2 before the bbc started series 1.
I say that because it is true. Instead of having a really long wait to continue the series they cut it to 13 episodes and at the end of the 13th episode it goes to volume 3 just as it went to volume 2 at the end of series 1 with Hiro in Jpan in the past.
There is a specific quote from Tim Kring the creator about how he thought they had got sidetracked a bit at the start of the second season. He went on to say that the second half of the season would pick up and be lot sharper, unfortunately this strike did bugger things up for them