57% of u.s. internet users on facebook. surprised?

According to eMarketer, 57% of internet users in the U.S. logged onto Facebook at least once a month in 2010. That translates to about 132.5 million people. In contrast, Twitter was used by only 9% of U.S. adult internet users. Facebook is clearly the leader in the social networking category but their numbers are starting to plateau. By contrast, I feel Twitter's numbers have much more potential for strong growth. Their challenge is clearly widespread adoption due to the fact that the Facebook platform is much easier for the layperson to comprehend and use.

Personally, for me they serve different purposes. Facebook is more my personal-stream and Twitter is more my news-stream.

Facebook's broad reach means that its once-dramatic growth rates are over; eMarketer forecasts single-digit growth in users after this year. On Twitter, growth rates will be higher, but relatively few online Americans use the microblogging service.