An Al-Qaeda commander, Abu Yahia al-Libi, said as much in a video released recently.
Saudi King Abdullah did indeed participate in the World Conference on Dialogue earlier this month. From the Foundation of Ethnic Understanding:
Soon after King Abdullah kicked off the conference at the ornate El Pardo Palace with a call for increased dialogue and understanding among followers of all religions, Rabbi [Marc] Schneier and Dr. Muzammil Siddiqi, one of the leading experts on Islamic jurisprudence in North America, had a private conversation with the Saudi monarch.
According to FoxNews (via AP), al-Libi said, “Bringing religions together…means renouncing Islam.”
“Equating Islam with other religions is a betrayal of Islam.” He calls for “the speedy killing of this tyrant.”