Seems the rumours were true, and Quentin Tarantino's fourth film will also be his fifth.

Miramax Films is taking the unusual and potentially risky move of releasing Kill Bill, the much-anticipated Quentin Tarantino martial arts action-adventure film, as two movies, the first opening in October.
Miramax will, in effect, be taking a three-hour film with a 200-page script and turning it into a serial. [...]
Kill Bill is Tarantino's first foray into action filmmaking.
When he approached Weinstein about making the movie several years ago, it was with the condition that he would be allowed to film all of his 200-page script. When Weinstein visited the set in its last month of shooting late last year, Tarantino said, Weinstein brought up the idea of splitting it in two.
Weinstein said it was not until he visited Los Angeles three weeks ago, when Tarantino showed him more than 90 minutes of the film, that the two decided on the two-film approach.

Reports that the second part will be subtitled Still Killing Bill have not been confirmed. At any rate, the report of an October release for part one is heartening; it'll be good to see if Quentin's kept his touch all these years away from behind the camera...