The earthquake of Revelation 11 will destroy a tenth of Jerusalem and 7,000 people, a figure consistent with the number of deaths that could occur in the event of a Temple Mount collapse. Concomitantly, the new Temple would survive the quake... and probably require some repairs, which in Hillelian fashion explains the seeming contradiction between two Jewish prophetic traditions that 1. the Messiah will not arrive until the Temple is built, and 2. he will commission the people to build the Temple when he arrives.
Another sign must apparently accompany the building of the Temple in the first place... the appearance of the red heifer. There is rumor of one having been found in March 2010 and being guarded closely by Jewish religious authorities. But, in order for construction of the Temple to even commence, the red heifer must be sacrificed on the Mount of Olives and its ashes saved for use in the Temple rites... without those ashes, there is no Temple service from what I understand of Jewish law and tradition. So, no red heifer, no sacrifice of it, no ashes, no rites, no reason to build a Temple. Look for it -- if they kill one atop the hill east of the Kidron valley from the Temple Mount and save the ashes, they're getting ready to start construction, and no destruction of the existing buildings on the Mount is necessary except for work that may need to be done in the Garden of El Qas.