His first official visit was in January, but that was in context of the reconciliation efforts between Hamas and Fatah. This visit appears to be more a reflection of Jordan's recognition of the Islamist revolutions taking place, especially in Egypt, and Abdullah's anticipation that Hamas' influence will continue to grow. Jordan is one of the last remaining Arab countries that can be described as moderate, and its leadership feels that it must not appear to be against the Islamist tide.
In January, officials said that the issue of re-opening Hamas offices in Amman were not raised in the talks, but Hamas now says that they will raise that issue with the king as well.
It appears that Hamas publicly re-engaging in terrorist activity by bragging of shooting rockets against Israeli civilians last week has actually helped it politically in the Arab world. Instead of being shunned more, a proud terrorist organization is now being welcomed as the effective leadership of Palestinian Arabs by the Arab world at large.
This is a good thing to keep in mind as people try to pressure Israel to make even more concessions for "peace."