got the same email. i ordered the same day they offered it.
We received your order for a replacement battery door(s) (MOTA855BATDR) for the DROID by Motorola. Unfortunately, this item is temporarily out of stock. We will ship your order for overnight delivery as soon as we receive additional inventory. Based on current inventory delivery schedules, you should receive your order between 1/12 and 1/20.
We appreciate your business and apologize for any inconvenience this may have caused.
EDIT: which is good because I got a free one a while ago and they gave me the same type of battery door as my old one. there was no difference. hopefully these will actually be the ones with the thicker padding.