While this frankly doesn't strike me as any more implausible than most other major religions, seeing this, um, summary of Mormon doctrine (much of which is out-of-date, I'm sure) is rather hilarious, in a scary Christian propaganda sort of way. I found it via Wonkette, who has some good commentary of her own on the situation:

Perhaps the Mormons were onto something with the long-disavowed polygamy of the 19th Century. Having multiple wives turns out to be good for the environment.