According to serebii.net, whom I trust, but not 100%, there will be a giveaway of a level 100 Regigigas from March 8th-21st at Toys-R-Us stores in the US. The Regigigas also unlocks new areas in Platinum where the three Regis can be caugth. I'm still waiting for this information to appear on Pokemon.com, but it probably won't until early March.