It's not official, but rumor that Blockbuster is preparing to file for bankruptcy in September is certainly believable. Expected even. According to several sources speaking to the Los Angeles Times, Blockbuster chief executive Jim Keyes along with representation from Blockbuster's senior debt holders met last week with the six major movie studios to announce the company's intention to enter a mid-September bankruptcy. Meetings that no doubt hoped to secure an uninterrupted flow of new content from Hol