We're very likely to release these games on Amazon's Android store and would like support for that storefront as well.
I'll make sure it's on the to do list. It might not be added in at the same time as the login or gamecircle integration but I can keep you updated on the progress.
Does that include receipt validation and integration into the BuyGoodsRequest process? (Probably the additional of an AmazonBuyGoodsRequest API call.)
We currently only support Amazon push notifications but Amazon Login and gamecircle integration are coming very soon.