The clamour for invites to Google+, the company's new social networking application, was huge last week, and it wasn't just us Average Joe's who were curious: Mark Zuckerberg has a Google+ account and has been looking around, gaining over 30,000 followers in the process. Although the Facebook CEO is guarded about who he befriends on Facebook, and is fairly quiet on both Twitter and LinkedIn, he has very publicly shown his hand on Google+, following its opening last week, as he sizes up the competition on an application that is widely considered to be the strongest competition that Facebook has ever faced.

Whilst Twitter differs quite significantly from Facebook in terms of structure and networking, the Google+ layout takes a similar approach to the 'profile' and 'wall' pages on Facebook, but has clearly been designed to usurp Facebook in two key areas: privacy and video chat. The inability of Facebook to provide flexibility in terms of privacy, particularly the lack of a user-friendly option to split friends into groups with different levels of access, has been remedied by Google+'s 'circles' function, where friends can be dragged and dropped into interlinking groups or 'circles' that have different levels of access to your information. The 'hangout' option in Google+ also enables webcam chats with multiple circles of friends, and is widely thought to have provoked Facebook's partnership with Skype, which will enable free voice and video conferencing through Facebook.

The Facebook-Skype deal is perhaps most telling of Microsoft's move to strengthen itself against it's longtime search-rival, Google. In 2007, Microsoft bought a 1.7% stake in Facebook for $240 million, and it recently purchased Skype for $8.5 billion. Skype SEO Tony Bates revealed to CNET that for himself and Steve Ballmer, CEO of Microsoft, better linkage with Facebook was the key behind the deal: "The day we announced, we definitely came to see Mark [Zuckerberg]...It was for both of us, Steve and I, the most important strategic relationship." The Guardian reported that Zuckerberg chose to play down the extent to which Google had prompted the Facebook-Skype deal, saying: ""I'm not going to talk too much about Google. Lots of companies that have not traditionally looked at social networking apps – not just Google – will be trying apps. I view a lot of this as validation of how the next five years will play out – every app will be social."

Early indications are that Google+ has been a massive hit during it's week-long 'invite-only' test phase, and has certainly wowed the early adopters in a way that Google Wave spectacularly failed to do. Whether Zuckerberg sees Google as his main competition or not, he is clearly aware that Facebook needs to up its game in view of strong challenges.