[gomaaa]

They're even wierder than I thought! I knew about the pouches, but not the rest of it!

From Wikipedia:
Marsupials are mammals in which the female typically has a pouch (called the marsupium, from which the name 'Marsupial' derives) in which it rears its young through early infancy. They differ from placental mammals (Placentalia) in their reproductive traits. The female has two vaginas, both of which open externally through one orifice but lead to different compartments within the uterus. Males usually have a two-pronged penis which corresponds to the females' two vaginas. The penis only passes sperm. Marsupials have a cloaca [1] [2] that is connected to a urogenital sac in both sexes. Waste is stored there before expulsion. The pregnant female develops a kind of yolk sack in her womb which delivers nutrients to the embryo. The embryo is born at a very early stage of development (at about 4-5 weeks), upon which it crawls up its mother's belly and attaches itself to a nipple. It remains attached to the nipple for a number of weeks. The offspring later passes through a stage where it temporarily leaves the pouch, returning for warmth and nourishment.

http://en.wikipedia.org/wiki/Marsupials

It's like having an alien life form in your own backyard!

[Virginia-American]

Marsupial weirdness:

At Talk Origins, they describe how embryonic marsupials develop an egg shell which is then resorbed, and how some are born with a caruncle (like an egg tooth).

Makes evolutionary sense.