I remember talking to Barrett Lyon over a year ago after he had already been in the business of defending mostly on-line gaming sites from DDOS attacks. I asked him what were the next most likely targets. He said the cyber extortionists would move on to first payment processor and then foreign exchange sites. Well, the first phase of this evolution is well underway. According to Netcraft StormPay.com has been under attack since Friday. Other large payment processors have experienced similar attacks.
Cyber extortionists go after high transaction volume sites because they are the most likely targets to cough up money rather than see an outage. If you rely on your web site for a significant amount of business beware. You will eventually be targeted by these guys. When they do you will have to scramble to re-home your servers, negotiate additional bandwidth from your ISP (as MilliondollarHomePage.com had to recently), and beef up your DDOS defense.
Of course you could always take measures before you were attacked. But who ever does that? It is so much easier to get funding for security *after* significant losses.