I haven’t seen a good answer to this question yet:
What happened in the 20 hours after Mubarak’s speech that forced him to resign?
According to various media reports, the military said- enough is enough.
Here’s an interesting take on the interim you were asking about:
Mubarak’s final hours: Desperate bids to stay
http://news.yahoo.com/s/ap/20110212/ap_on_re_mi_ea/ml_egypt_mubarak_s_final_hours