THR.com has an exclusive that establishes / clears up the planned releases of the two-part adaptation of The Hobbit:

Warner Bros. is scheduling Peter Jackson and Guillermo del Toro’s
two-part adaptation of The Hobbit for December 2012 and December 2013. A confusion over release dates surfaced earlier today when
IMAX announced
an overall, 20-film, three-year deal with Warners. In outlining which
films would be included, IMAX incorrectly gave 2013 as the release date
for the first Hobbit movie.


A couple of weeks ago, Peter Jackson spoke as to some delay rumors and cleared up a few things himself.  So with that and this announcement, things seem to be solidifying on the dual productions.  So, it’s not 2011 as some originally planned, but it’s also not 2013 as the earlier IMAX announcement stated.