This graphic came from Joel Comm's twitpic account. It shows the growth relationship of Twitter, Facebook and MySpace. It may be difficult to read in this graphic (although you can click through to his twitpic and view much larger). But the green line is Facebook and you can see the incredible volume there. Twitter is the orange line at the bottom -- while the numbers aren't as big, the % growth is huge. And MySpace, as you know, is declining but still has moderate volume.
A quick recap:
Facebook: 122+ M unique visitors, 8.5% growth last mo, and 250% annual growth.
Twitter: 23 M unique visitors, 16.5% growth last mo, and 1,164% annual growth!
MySpace: 61 M unique visitors, 7% growth last mo but 5.6% annual decline.
When building a personal or business brand utilizing the social networks, you have to be where the people are, where the eyeballs are congregating. Kind of difficult to pass up 122+ million unique visitors on Facebook. So it's extremely important to have both a personal brand and business brand strategy for Facebook and Twitter, and I would add LinkedIn because of the demographics. And if you're in the music field, particularly an artist, MySpace is still a must.
If you have any questions about growth of social media or you feel you're not using them to the best of your advantage, shoot me an email and I'll be happy to answer you.