Does Social Networking makes your brain grow?

With thanks to Rob Cubbon Ten year ago, we were hearing that London Taxi drivers have an enlarged hippocampus because of their encyclopedic (or should that be atlassian?) knowledge of London's roads.

Now the same research team in UCL are questioning whether social networking has a similar impact although the researchers do confess:

It's not clear whether using social networks boosts grey matter or if those with certain brain structures are good at making friends. perhaps slightly cyclic reasoning?

I've wondered for a while whether we have a finite "namespace" in our brains, and once it's full (see why I didn't make it as a neuroscientist!), it starts to overflow and we forget people's names.

I can testify that changing my work relationship pattern from a single slowly-evolving large corporation to short assignments in 100 client organisations over the last 6 years has certainly helped to fill it up. My wife reports similar name-overflow challenges working a supply teacher.

Or perhaps it's just that we're just getting older!