The final shiny Pokemon, Suicune, is available to download through this coming Sunday, February 6th.
You appear to need all three shiny Pokemon for Pokemon Black and White. When you transfer them to Pokemon Black or White you will unlock the ability to catch the new Pokemon Zoroark. Zoroark will otherwise not be obtainable in the game.
And, while you are out on your download mission, you might as well stop by your local Toys R Us to download Ash’s Pikachu. The download event for Ash’s Pikachu runs until February 13th.
That will then be followed in some areas by the Pokemon tour.
And then, finally, Pokemon Black and White will ship on March 6th, at which point we can actually sit down and play the game!