Out of the seven social media platforms considered in web analyst firm StatCounter's latest look at social media websites as drivers of traffic, Facebook unsurprisingly comes in with nearly half of all traffic.

The site takes a look at social media driven traffic and gives us a look at how the lay of the land has changed over the past year.

The top three social media sites a year ago were StumbleUpon, Facebook and MySpace, in that order.

Now, Facebook has taken a clear lead, with nearly half of driven traffic, with StumbleUpon in a surprising second place position, accounting for nearly a quarter of all traffic, and Twitter just behind that with one out of every 10 hits to websites from social media. Myspace, on the other hand, has virtually disappeared, dropping from 16% of hits to nearly 1% this month.

It will be interesting to see where these numbers go, as yesterday Facebook announced some very interesting changes to its platform, including a web-wide "like" button, that shares a user's activity with a single click. With Facebook already dominating social media driven traffic, we have to wonder if this number will only skyrocket with the new sharing and recommendation functionality.

The same can be said for Twitter, which last week announced Annotations, a whole new meta-layer of data which will be appended to tweets. This new feature could add some seriously interesting new functionality in this summer and increase Twitter's already strong presence as a driver of traffic.