Don Dodge, Developer Advocate at Google, has posted to his personal blog (and shared via Google+) how to transfer Facebook friends to Google+.

“Facebook has intentionally made it difficult for you to manage your friends list or move them anywhere else,” he says. “There are several third party tools to help you do this and they all work in about the same way. Facebook is also actively shutting down or blocking these tools so you may want to do this sooner rather than later.” He then provides the following steps:

1. Set up a Yahoo email account if you don’t already have one. It only takes a minute. Unfortunately, you can’t use Gmail because Facebook has blocked it.
2. Sign into your Yahoo mail account using Facebook.
3. Go to email, click Tools, select Import from Facebook. You may need to try this several times for it to complete.
4. Go to the Tools menu and select Export to CSV file. Give the file a name and save it to your desktop.
5. Open Gmail and click Contacts, More Actions, Import. Browse to the CSV file you just imported.
6. Give the New Group a name like “Facebook Friends” and begin the Import
7. Go to Google+ Circles. Your imported Facebook Friends will show up under “Find & Invite”.
8. Add these friends to the Circles that make sense to you. You can also create new circles and invite them into those circles.

He also links to the following video:

Getting people to leave Facebook for Google+ may be the biggest challenge Google faces in growing its user base. Sure, you can use both, but if everyone you communicate with on Facebook is on Google+ how many reasons will you have to stay on both?

Of course Facebook has a lot of things going for it that Google+ doesn’t at this point. For example, the countless apps that users have grown accustomed to (or in some cases even addicted to) using. Farmville players, I’m looking at you. That said, Google has also been making acquisitions in the gaming realm, so I doubt that this kind of thing is far off for Google+.

The more Facebook friends Google+ users are able to get on Google+, the more useful Google+ will become to users. It means reasons to stay engaged with the service. Without your friends, it’s just a cool concept that will never materialize to much more than another news reader-type tool (much like Twitter for a lot of people). With real friends (like Facebook), it will become harder to leave.