There is some pretty big news in the “March 2009 Global Faces and Networked Places” report on social networking from Nielsen, one of the leading global marketing and media information companies.

According to the report, “two-thirds of the world’s internet population visit social networking or blogging sites, accounting for almost 10% of all internet time….That percentage is likely to grow as time spent on social network and blogging sites is growing more than three times the rate of overall internet growth.” The report goes on to state that time spent on social media sites has overtaken personal e-mail “to become the world’s fourth most popular online sector after search, portals, and PC software applications.”

Transversely, however, the report identifies a not totally unsuspected trend: As these social networking sites become more attractive to advertisers, they become “less appealing to members who see highly-targeted ads as invading privacy.” Consumers are actually growing less tolerant to advertising on social media. And, more social media users now consider advertising on social networking sites to be an intrusion; even the number of those respondents who don’t mind being served ads if they are relevant to their interests is dropping.

What does this mean for smart marketers? That content, and the way it is delivered and transmitted, is becoming more complex than ever—and that companies must undertake careful studies of these channels before engaging them. Additionally, it also seems to indicate (though indirectly) that the e-mail component of any online campaign must be fully considered in the context of greater social media usage, necessitating more formal integration of e-mail content with social media content.