By-invitation-only Brightkite is a location-based social networking site where users keep nearby friends and the rest of the universe up-to-date with what’s going on around them through check-ins, posts and photos.

Checking in:   Either on the web or when out and about, users update Brightkite by checking in with their location, a note or a photo.  Check-in locations can be an exact address, an intersection, a city and state, or a country.   At a business location? Simply type the name of the business, such as “Paradise Bakery,” and a list of available addresses in the area of your last check-in for businesses with that name will be returned for selection.   Brightkite updates your location and displays other Brightkite users that are currently there or have been recently.

Privacy settings:  Brightkite’s two privacy modes are public and private.  Public displays the check-in location (as it has been submitted) to everyone.  Private mode allows various levels of privacy measures to be set.   When using public mode, be sure and exercise a level of caution as anyone on Brightkite can see the post.

What’s happening? Users can track their friends’ locations or people that are:

♦ Close by or within 20 meters
♦ Within a block or within 200 meters (yeah, first two can be kinda creepy for the ”When A Stranger Calls” generation)
♦ Within the neighborhood or 2000 meters
♦ Within the area or 4000 meters

Placemarking: Placemarks are bookmarked locations that are frequently used such as home, work, etc. and enable speedy check-ins.  Users simply SMS @work or @home (or whatever you named the location) for speedy check-ins.

Businesses: If you have a retail business, use the Search Posts feature to find when you are mentioned by users in their posts or check-ins or better yet, add the place feed to your website or blog.