One of the biggest reasons for the spam increase is the fact that spammers are now taking advantage of old, reputable domains; and social networks are an easy target. Many spam messages contain nothing more than a subject line and a link, which leads to a social networking profile, created with a random name.
Traditional CAPTCHA protection is not very effective anymore, and social networks will have to investigate other ways of protection if they don't want to become a haven for spammers and phishers because frankly, lately it really looks that way. The report mentions a new kind of CAPTCHA, a photographic image that requires the user's interaction "in a way that would be very challenging for a computer program," and we'll probably be seeing more of it on major social networking sites very soon.
Oddly enough, the report does not mention a big increase in phishing attacks, which are up only 0.11% compared to April. However, the report only mentions that "one in 279.7 (0.36%) emails comprised some form of phishing attack." Lately, however, phishing attacks have been spreading like wildfire on Facebook and Twitter; it would be interesting to see an analysis of this type of phishing attacks compared to traditional email phishing.