Has Twitter gone mainstream? Sure it's gaining in popularity, but mainstream? I think not. Mainstream is defined as follows:
The prevailing current of thought, influence, or activity. The people or things representing the most common or generally accepted ideas and styles in a society, art form, etc.
At most you could quantify Twitter as mainstream for a subgroup of Internet users. But why quibble when I have real data. Here are the results of a Vizu Answers poll I conducted on December 29, 2008 across 286 websites.
The results show that 1 in 5 use Twitter while a full half of respondents didn't even recognize Twitter.
Twitter is not mainstream. So, what is it? I think it makes sense to measure Twitter using the Everett Rogers Diffusion of Innovation.
Rogers proposes that adopters of any new innovation or idea can be categorized as innovators (2.5%), early adopters (13.5%), early majority (34%), late majority (34%) and laggards (16%), based on the mathematically-based Bell curve.
Using this measurement and the poll data (20%) we see that Twitter is entering the Early Majority, which is likely why the buzz quotient for Twitter has increased of late. Twitter will need to make its way through the Early Majority to the Late Majority before it truly becomes mainstream.
Of course you could argue the merits of the data. But this was an Internet poll which means it likely under reports Laggards. You might also point to the figures recently released in Hubspot's State of the Twittersphere.
The growth is impressive. But I'd point out that Twitter users often maintain more than one account. Here's an unscientific FriendFeed poll that, at the time of writing, indicates that Twitter users maintain an average of 1.5 accounts.
So lets wait to annoint Twitter as mainstream and instead see how it evolves and innovates in 2009.