Source: The Register
SecureWorks claims that the number of hosts infected with the Storm Worm has gone from thousands (in January through May) to millions (in June and July) -- a nigh-thousandfold increase. They offer some speculation on the impact of this.
I speculate that it is primarily driven by phishing, and that the worm is primarily being used as spyware to obtain authentication credentials. I say this because I have noted a distinct drop in phishing email at the same time I've seen the increase in "e-card" spam characteristic of the Storm Worm.