We've shown you how to make Google+ look like Facebook, and fiddle about using Yahoo to add your contacts…but now: pay dirt! Facebook Friend Exporter is a Google Chrome extension that makes the process easier—but be quick, it'll probably be blocked by Facebook anytime now. Update: It took a whole 24 hours, but Facebook has caught on.
The current version of Facebook Friend Exporter is blocked, but the author says he's looking into a work-around. Stay tuned.
You see, we're not supposed to "access Facebook using automated means (such as harvesting bots, robots, spiders, or scrapers)." Still, for the moment, the the Facebook Friend Exporter Chrome extension lets you export contact data as either a CSV file or directly into Gmail ready for Google+.
Seems to have worked for me, but Angus over at Lifehacker ran into a few problems.
Bonus Tip! The author of this extension also has another called Extended Share for Google Plus. It gives Google+ the ability to easily share posts via Twitter and Facebook. Nice one.