These are the same ones that were released in Japan with the games, so if you couldn't get them then, now's your chance. At least, if you live in the US - no word yet on whether these bonuses will come to other regions.
Pokemon.com notes that the Ho-Oh figure is 2.25 inches tall, while the Lugia figure is 2.5 inches tall.
Both figures were made by the Japanese company Kaiyodo, renowned for their figurines and garage kits.
As always, these sorts of bonuses are contingent on availability and participation. So, before you go out and place your preorder, it might be beneficial to call the place ahead of time and ascertain if a) they're participating in this offer and b) if they have any left.
Pokemon HeartGold and SoulSilver release in the US on March 14.