We're looking at cloud computing in my firm as well. Our use profile is pretty good according to this article. We have our own systems that can handle our baseline traffic (and then some) and we have predictable periods where traffic will spike, which is when we're going to spin up lots of VMs to handle those peaks.
CAAK is fantastic... and yeah, the spammers were there long before the big firms had clouds anywhere other than in the heads of their executive level management.