The course of social media never did run smooth — not for long, anyhow. And for some Web 2.0 companies, it's running less smoothly than ever.

Without question, Facebook is the network du jour; but even though the reigning champion's user stats keep soaring, social networking as a whole might be leveling off. Nevertheless, scores of other highly competitive social sites keep waxing and waning; and different networks and apps are more popular in specific geographic areas, with certain genders or age groups and even among various social classes.

For example, Plaxo is the network with the most users over the age of 65. Facebook is more popular with women, but Digg and Reddit tend to be more popular with men. LinkedIn is the "richest" social network, but Plurk outranks it when it comes to well-educated users who have graduate degrees.

Check out this infographic from social media agency Ignite Social Media, and let us know what you think in the comments. Do these findings line up with your own perceptions and usage habits?

Click image for full-size version.

Lead image courtesy of iStockphoto, BeholdingEye.