this is the Kenshin Festival's 82nd year (the first festival being held in 1926.)
The main rumor is that Gackt will be participating in the festival - especially during the "taking of the field" part of the ceremony - which sounds like it is a reinactment of some type. Its hard to translate that properly.
If its a reinactment, it will most likely be Gackt in the role of Kenshin, which he currently plays on NHK's Fuurin Kazan.
**Fuurin Kazan Spoilers** (for those who don't know the history.)
Uesugi Kenshin was a warlord in the feudal period of Japan - The Sengoku period to be exact. He is most famous for the battles with fellow Daimyo, Takeda Shingen. He and Shingen fought 5x at Kawanakajima, but both being cautious- the "battles" never amounted to more then Skirmishes. It was in the 4th battle, that the famous Yamamoto Kansuke (of whom Fuurin Kazan is mostly about) lost his life.
Takeda and Kenshin thought highly of eachother, and respected one another greatly. When Shingen died a few years before Kenshin... Kenshin mourned the loss of his greatest rival, weeping openly, and swearing to never attack Takeda land. He eventually became a Takeda Ally, not long before his own death.
for more information on this festival, please visit the links below
Kenshin Festival 2
Pronweb Watch article
for more information on Uesugi Kenshin, for whom this festival is held... please visit these links
My Brief Kenshin report (Rumors and Facts)
Uesugi Kenshin (Nagao Kagetora) Wikipedia
Purchase Samurai Banners of Furin Kazan, a great book
Purchase the original 1969 movie