jdMorgan - 7:56 pm on May 6, 2008 (gmt 0)

Googlebot would see the DNS change, and it would also see the short Time-To-Live setting that I recommended. I can't assure you what they would do because I don't work there. All you can do is the use the DNS and HTTP protocols as-specified, and hope that, as usual, they pay attention to the "messages" sent using these protocols.

I agree with bwnbwn that a fully-operational back-up site is the preferred solution, but I assumed that you were willing to risk some delays to avoid the cost and complications of a fully-live backup site.

Jim