"This dropdown menu will be expanding over time to include smaller groups of people you may want to share with, like co-workers, Friend Lists you've created, and Groups you're a member of. These will make it easy to quickly select exactly the audience you want for any post," Facebook's blog post said.

Since launching Google+, Google has been claiming that its site offers a simpler, more effective way to share content than Facebook. Google has said that Facebook's privacy and content-sharing controls are too complex and inconvenient, leading users to often share inadvertently with a larger audience than intended.

While the jury is still out on whether Google+'s Circles feature indeed offers an improvement over Facebook's functionality, Facebook's move today clearly seems motivated to address any competitive advantage Google may be trying to get with Circles.

Google+ Vice President of Product Bradley Horowitz said Google deserves part of the credit for Facebook's changes.

"I think it's good for users, which is exciting for us. The reason we wake up in the morning is to build great experiences for users, and I think what they did was familiar and good for users," he said during a webcast interview with Tim O'Reilly, CEO of O'Reilly Media, on Tuesday afternoon.