I don't like this. Mormons can be decent people, but as Muslims we need to be careful who we associate ourselves with. Allah says in the Quran (translated): "Your real allies are Allah and His messenger, and the believers who observe the prayers (Salat), and give the obligatory charity (Zakat), and they bow down...do not befriend those among the recipients of previous scripture who mock and ridicule your religion, nor shall you befriend the disbelievers. You shall reverence Allah, if you are really believers. "
By revering Joseph Smith, a self-claimed Prophet, they are indirectly mocking the position of Muhammad (PBUH). Mormons are barely Christians, as they hold Joseph Smith in higher regard than Jesus (AS). They are no "allies" of ours.