I have no doubt that in 2010 and beyond Social Media will play a more dominant role in the enterprise marketing strategies.

Of course on-line Marketing and Social Media is a subject that contains more areas than the Social Networks listed here.

This overview is an excellent quick start on the most used Social Networks.

The original post can be found at: A CMO's Guide To The Social Media Landscape. On their site you can also find a PDF with a higher resolution image.