Is Darabont still connected with the series?
No longer, but he's still listed as developer in the credits. Season 2 will be divided into 2 main story arcs: the first seven episodes comprise one arc, which will end on November 27, 2011. Then the series will go on hiatus and return on February 12, 2012 for the next six episodes, which comprise the second story arc.
Though AMC won't confirm it--anything about Darabont's firing is considered off-limits to press--people in the know have stated that Darabont's final involvement with
The Walking Dead is Season 2's first arc, and new showrunner Glen Mazzara takes over with the second arc in 2012.