Khalaf has a very interesting post about tensions between Jordan and Hamas going on right now. I had no idea of the history between the two. One of the big current issues seems to be that "A few days ago, another Hamas leader, Mohammad Nazzal, made the astonishing statement that Hamas does not recognize the disengagement decision of 1988, by which Jordan renounced claims to the West Bank and withdrew Jordanian citizenship from residents of the WB."
Jordanians are afraid that Hamas will try to interfere again with internal Jordanian affairs and to try to wrest power there. Nu, go read the post there's lots more.