The team at the research firm Sucuri announced a serious vulnerability to W3TC and WP Super Cache this afternoon. (Update: it appears the vulnerability was first reported on WordPress.org about a month ago.)
There is currently a significant attack being launched at a large number of WordPress blogs across the Internet. The attacker is brute force attacking the WordPress administrative portals, using the username "admin" and trying thousands of passwords.
At CloudFlare, we're always looking for ways to eliminate bottlenecks. We're only able to deal with the very large amount of traffic that we handle because we've built a network that can efficiently handle an extremely high volume of network requests.
The New York Times this morning published a story about the Spamhaus DDoS attack and how CloudFlare helped mitigate it and keep the site online. The Times calls the attack the largest known DDoS attack ever on the Internet.