Recommendations will be based on factors like mutual friends and game level, and will include names and profile photos. When you add a Zynga Recommended Neighbor you and your new neighbor will be able:

Visit each others gameboard and perform neighbor actions send each other free gifts and other game requests. You don't have to be Facebook friends to play games with Zynga Recommended Neighbors. You will be able to send and receive Facebook Game Requests and Zynga Neighbors may access your public Facebook Profile.

Note:

If you chose not to be recommended, you may still receive recommendations for Zynga Neighbors and may rejoin the program at any time. If you have already accepted a Zynga Recommended Neighbor and wish to remove them, visit the neighbors tab in the game.

but it's unclear where this image comes from exactly, as the Zynga home page does not have a log-in option that you're aware of. And RewardVille only allows log-ins via Facebook with no customization options. Guess is that this is part of the upcoming Project Z initiative, which will supposedlyga games network outside of Facebook but powered by Facebook.