What's the Mormon view of Freemasonry?

I've got the idea from somewhere that Mormons aren't allowed to be freemasons. Is this true? If so, what is the reasoning? I think I've heard allegations of similarity between Freemasonry and some Mormon temple activities (neither familiar to me). How are such claims answered by the LDS church? Related: https://christianity.stackexchange.com/questions/3947/is-freemasonry-appropriate-for-a-christian