This entertaining article explores all corners of the fairly recent hydrological work being performed on the Great Sphinx to nip in the bud any possible future water damage to the ancient (and don't forget mysterious!) monument. A video accompanies the information, which also gives lip service to Hawass and Lehner's conclusion that there aren't any subterranean chambers hidden under the Sphinx. Argh! Thanks for ruining it for all the day dreamers :P
The following is an article at Zahi Hawass' Blog of his and Lehner's work at the Giza Necropolis.