This is copied from Serebii in case any of you haven't seen it yet.:
The new issue of Nintendo Power has supposedly announced the US dates for the giveaway of the final fourth generation Pokémon, Arceus. According to it, Arceus will be given away in Toys 'R' Us Stores across America from November 7th to November 15th onto your Diamond, Pearl or Platinum games. This Arceus will unlock a special event in Platinum which gives some of the theoretical back story of Arceus and when transferred to HeartGold & SoulSilver, it unlocks a special area called the Shinto Ruins and gives you access to a Level 1 Dialga, Palkia or Giratina. Click the picture to go to the HGSS page.