Anyway, I'm sorry to be a negative Nelly, but I can't bring myself to believe that it hasn't been cancelled.
I think that there is absolutely
no chance that the 26 episodes of Season 1 will not be completed. In fact, I would guess that the remaining 13 episodes are already done. (We already know that episode 14 is done.)
The lead time for animation of this type is
huge. (Don't confuse this with South Park, which is just thrown together by a much more limited process.) If Warner Animation was going to wait to see what the reception of the first half (13) episodes was going to be before spending any money on the second half, we won't have the next set until 2012.
And there is no reason not to do Season 1 as a complete set. Scooby-Doo isn't a new concept looking for an audience, it has a world wide, loyal audience. Mystery Inc. will be seen on TV (and sold on DVDs) in numerous languages around the world... For many, many years to come. Not completing a story arc would damage the money making capacity of the episodes that have already been shown.
If I had to bet, I would say that the production team already has a good start on Season 2. Scripts take more time when you are plotting a 26 episode arc. And then there is lining up the voice talent, and doing the recording... and coordinating with the Korean animation company. And the translation and recording in other languages... and any post-production...
None of this precludes the possibility that there could be some difficulties between Cartoon Network and Warner Animation. But even that would be an inter-family argument, since they are both owned by Time/Warner, and any disagreements can be fixed by an Executive Decision.
GLT