They were bringing back 600, apparently - link.
That was last year's CES, a year ago now and nothing else has been mentioned.
Polaroid (erhm the empty shell of a company that just used the Polaroid name) has stated multiple times they have no plans to ever produce film again. Hence the Polaroid (Fuji) 300.
The camera announced last year, according to The Impossible Project was supposed to be released with PX600 film. The film however was not up to the standards that Polaroid wanted so the idea was shelved and eventually discarded all together.