One acronym: GSLB (Score 1)

Best bet for DR web hosting is duplicating the applications in two or more physically different locations.
In order to realize some return on such an expensive deployment, you need to be able to sweat all your assets. the only way to do that cost effectively is by adding some sort of load balancing across these applications. Most frequantly used solutions for hese types of environments are DNS based load balancing. Both Cisco and Radware offer a GLSB solution. In my experience, and I'll probably be killed for this, but the Radware solution is better.

my 2c

PS. i work for an independent integrator and not for either vendor.