Israel's "Team Twitter" set in the context of the Israeli state's broader propaganda efforts.
US military blog
The attacks seemed to come in two waves.
The first was a spam campaign consisting of e-mails with links back to posts by Cyxymu. This drove some traffic to the blogger's postings on various social-networking sites, possibly to disparage him as the source of the spam.
The second and more destructive phase consisted of the denial-of-service attack, which attacked the sites' servers by sending it lots of junk requests — presumably to prevent people from reading his viewpoints.