One of the best east coast hackerspaces, http://www.nycresistor.com/ has practically made it the official drink of the place.

Thanks for the link! I've been wondering where I could take some beginner classes for arduino and the like, but now I know.

It's everywhere in Budapest: http://www.clubmate.hu/#map

I've seen it in almost every shop in Hamburg. In other regions it's more a few group of people that drink it. In my university it's quite popular for instance.

It's now available in every larger supermarket even in mid-sized west-German cities, like here in Wuppertal. So somebody must drink it.

In hacker spaces it's everywhere.

The company I work for has always a few Club Mate in the refrigerator.

In Düsseldorf/Germany.

It's also available in Hamburg, Leipzig and other German biggish cities.

When I visited the university of Göttingen, it was everywhere. Students also seem to have it adopted as the drink of choice.

It's now available in supermarkets in rural NRW. So, I don't think "only Berlin" is remotely true anymore.