Why did the 700 Billion Bailout plan fail?

As of today (Oct 2, 2008) it is too early to say the plan failed. The bill as presented in the House of Representatives on September 29, 2008 did not have the necessary votes to pass. Various reasons have been given for its initial failure to pass, including the unpopularity of the bill among residents (as gauged by polls) and the lack of oversight. However, a revised bill now has passed the Senate as of Oct 1, 2008. See "bailout deal" under Wikipedia for additional details.