I usually try to avoid simply re-purposing other blog content here, but this article from eMarketer is a beauty. The fact that 1/5 of all display ad impressions during July took place on social networks gives testament to the growing importance marketers are placing on reaching consumers in that space - as well as the increase in clutter among social ads. How long can social network ad channels remain relevant before consumers start to tune them out like most other forms of display advertising? Or, are we already there? Methinks the latter.
"According to comScore, the top 20% of social network users visit networking sites 2.4 times per day, on average, and spend 31 minutes on them—twice as long as the same users spend with e-mail or instant messaging. And that, in turn, means more time with ads."