The topic was barely whispered of during the Final Fantasy XIII party earlier tonight in Tokyo, but the game's latest press release has confirmed that there will be a PS3/FFXIII bundle in Japan.
It'll be a Slim PS3, will include a copy of Final Fantasy XIII and...that's all the info they had. More information will be provided "in the future". Expect the finer questions, like price, availability and the most important of all - whether it'll be a custom, FFXIII-branded console - to be answered at the Tokyo Game Show in a few weeks time.
UPDATE - Sony sent out a press release this morning for the bundle, indicating that it would be out on December 17 (same day as the game in Japan) and...that's it. How helpful.