From the AFP:
Egypt will close the Great Pyramid of Giza on Friday to avoid any rituals by a group rumoured to have plans to mark the date of 11/11/11 at the site, an official said.
The decision came “after much pressure” from Egyptian Internet users that strange rituals were going to be held “within the walls of the pyramid on November 11, 2011,” Atef Abu Zahab, head of the Department of Pharaonic Archaeology, told AFP.
The Supreme Council of Antiquities confirmed the closure Friday of the tourist site, in a statement that only referred to the need for maintenance following a busy period during Muslim holidays.
Some attribute the number 11 to paranormal powers that provide a channel of communication with the subconscious, others see a mystical connection between the number and disasters, like the 9/11 attacks on the United States.