Twitter is now just as well known as Facebook, though it has far fewer users, says a report titled "Twitter Usage in America 2010" from Edison Research and Arbitron.

Nearly nine out of 10 Americans (87 percent) know about Twitter, though just seven percent (17 million total) use it, says the study, which includes three years of tracking data and a telephone survey of 1,753 conducted in February 2010. That 87 percent is compared to just 26 percent who knew about Twitter's existence last year. (Facebook had 88 percent awareness among those surveyed, with 41 percent saying they had a profile.)

Despite the relatively small number of users, what respondents said they use Twitter for suggests it could have a powerful effect on your brand. (The effect could be good or—in the case of say, someone Tweeting about lousy customer service—bad.) Forty-two percent of respondants are using the service to learn more about products and services, and 41 percent are using it to swap reviews. 

If you're still debating a Twitter presence for your company (or too busy getting a handle on Facebook first), consider this: More than half of Twitter users surveyed said they follow brands on the platform – and this group is three times more likely to follow a brand on Twitter than they are to follow a brand on Facebook or any other social network. Asked "Do you follow/friend any brands or companies on social networks" 51 percent said they follow on Twitter, compared to just 16 percent on other social networks. 

Other nuggets from the study: African Americans make up about 12 percent of the U.S. population, but they account for 25 percent of Twitter users.

By far the largest fraction of Twitter users – a third – are between the ages of 25 and 34, followed by 35- to 44-year-olds (19 percent) and 12 to 17-year-olds (18 percent). Twelve percent of Twitter users are between the ages of 45 to 54, and 11 percent are between the ages of 18 to 24. Women edge out men in the demographics: 53 percent to men's 47 percent.

Twitter users are well-educated (30 percent attended a four-year college, compared to 19 percent of the general population) and relatively well-off (nearly half have a yearly household income above $50,000.) They're also not the first in line to try the newest things – the biggest fraction (29 percent) said they would tend to buy or try new products at the same time as others. A quarter of Twitter users said they were second in line for new things – not the very earliest adopters, but not back with the rest of the pack, either.

And speaking of early adoption, if you're thinking of being among the first to try advertising on Twitter but wondering if it will turn off users: Half said the new "promoted tweets" would have no effect on their usage, while a third said they'd stop using the service or use it less.