Google Buzz started to roll out to Gmail users this evening in a move said to challenge Facebook and Twitter.

1. It’s available immediately to all Gmail users; unlike Google Wave it isn’t restricted to beta users. According to Google it will appear in your inbox in the next day or so
2. Google Buzz is a realtime social network like Facebook, Foursquare and Twitter. You can use it to share links, photos, videos, and status updates with your network
3. Updates from people in your network will automatically be posted your Gmail inbox
4. The network will prioritise messages from people in your network that the Google Buzz algorithms determine are most relevant to you
5. Google Buzz incorporates a function similar to Twitter’s retweet. Users can recommend posts that might be of interest to other people in their network
6. You don’t need to build another network as you’ve done before with networks such as Facebook, Foursquare and Twitter. Google Buzz will use your email history to build out your network. If Gmail isn’t your primary email client consider importing your address book from other email clients
7. Using the Google Buzz application on your mobile phone (iPhone and Android) will enable you to include a GPS-generated location with your updates
8. Updates will be made available to everyone in your network and indexed by Google as a default. Privacy settings and user-defined groups will enable information to be locked down
9. An enterprise version is in the works for companies that want to use it as a social communication platform
10. Is a competitive threat to other social networks? Potentially, but it depends on uptake. Gmail has 175 million potential users. Facebook has 400 million users. Twitter has an estimated 25 million users