There is always an ominous shadow that lurks over the kickboxing world like a storm cloud ready to burst, and that is K-1 and when things will get announced, if ever. K-1 has the Japan MAX tournament coming up later on this month, but that still doesn't explain the heavyweights. There have been many rumors, mainly from fighters who have been contacted about the event, that K-1 will indeed put on a K-1 World Heavyweight GP. It's Showtime head Simon Rutz confirmed this by not planning a show for late November/early December featuring big heavyweights as he had planned and pushed the show back to January.
K-1 will have an announcement on their UStream page (http://www.ustream.tv/channel/k1-Channel) on the 15th at GMT+9/PDT+16.
There have been no hints from K-1 as to what the subject matter will be, but the background of their UStream profile is photos of Badr Hari and Semmy Schilt, which could indeed be a hint.
UPDATE: K-1 just posted that they are announcing details about the World Grand Prix Final 16 in Nanjing, China tomorrow. The press conference will stream live at 7:00 PM Japan time, 6AM EST for those in North America. Among the details are the participants and the venue being used. Huge news!