Now that Heart Gold and Soul Silver are to be released a few details about the game have been revealed. As such we've seen that the starter Pokemon actually follows you, like in Yellow, which is pretty cool. Also, we've seen that the houses look a lot like those in the other 4th Gen series. Last but not least have we witnessed the appearance of Pikachu colored and Notched Ear Pichu in the Ilex Forest.
I say it's an event involving Celebi.
I say it's an event involving Celebi.