For anyone who missed Shiny downloads at Gamestop, don't despair! As it turns out, Nintendo has decided to redistribute them this month over Wifi! Just like the Gamestop downloads, there will be a different one given out roughly every week the month of February. These shiny beasts are basically identical to the ones given away at Gamestop, with the exception that they have a different OT. The Gamestop events had the original trainer "Gamestp" whereas these will be original trainer "WIN2011."
As with the events given away from Gamestop, these will also unlock Zoroark if you send them over to Black and White. Similar to when Nintendo had the Gamestop Shiny Pichu download, and then distributed them over Wifi, if you already downloaded these to one of your games you cannot download the same one over Wifi. Basically, if you got Shiny Raikou from Gamestop you cannot get the Wifi Shiny Raikou download. However, if you missed one you can (for example you got Shiny Raikou from Gamestop, but forgot to pick up Shiny Suicune.. you CAN download the Shiny Suicune).
All of the dates you can download these shinies are on the left in the Upcoming Events toolbar.