The official Pokémon Japan website has announced that Pokémon will be at an annual Kyoto festival for college and university students.
Not all details are known at this time. The announcement states that more details will be revealed on Friday, October 1. This will probably announce more universities and what the Pokémon might be.
To celebrate the release of Pokémon Black and White, attendees are invited to bring the DS and Pokémon games to trade and battle other players on October 10, 2010. They can also receive one of the event Pokémon being distributed.
Source: http://www.pokemon-sp.jp/news-sp/2010/09/0924_01.html