For those of you who have Black and White, but did not get a chance to download Victini over Wifi... The event is now active again! If you want to download it, simply connect to the Nintendo WFC using Mystery Gift. This runs from June 12, 2012 to June 26th, 2012.
The Mystery Gift is to go along with the release of the Pokémon White: Victini and Reshiram/Pokémon Black: Victini and Zekrom in Europe. Since Mystery Gifts are set up regionally, this allows any English game to download it.
If you already downloaded one, you can't download another to that particular game.
Victini will be a Lv 50, and has Fusion Flare and Fusion Bolt.