Now that's a nice rumor! According to some dubious 2ch
source, a new
Darker than Black TV anime series will start airing in Japan from October! The report claims that the third anime (not counting the 2010
OVA) will be titled Darker than Black: Nanpou no Houkou - among other alternative spellings for the subtitle, which roughly translates to "Wandering through the South".

Some staff names are also being indicated, but since the claims are purely anonymous for now, we're better off waiting for a more official notice on this matter. Just for the sake of speculation, though, it's worth pointing out that studio Bones - who animated the first two DTB series - has no other project announced for this year (that I know of, anyway), beyond the ongoing series
Eureka Seven AO and its complementary
OVA. And that the new Eureka anime will end just beofre the Fall 2012 season. So it would be no surprise if they do confirm this third season of Darker than Black.
The second season,
Darker than Black: Ryuusei no Gemini, aired in Japan from October 2009, following the original series from April 2007. About time we got a continuation, then!
I'm a fan and everything but I don't like when people start to scrape the bowl.