When you click on the button, a new window pops out and you can choose between posting the page to your profile, emailing it to your contacts or bookmarking the page using services like del.icio.us or furl.
A profile page is public and can include information about yourself, a photo, links to your sites. You can select the photo from one of your public Picasa Web Albums. Here's the profile of Kevin Marks, a former Technorati engineer who now works at Google.
This page lets you see the latest web pages shared by your Gmail contacts:
There's also a page that lists all the popular items shared by Google users, but some of them are questionable (I saw pages that only had a single view):
... and a way to see popular items from a domain or for a tag:
You can also subscribe to feeds for all of these pages, but it would be nice to have a special feed for your contacts and gadget that keeps you up-to-date.
Overall, the service adds the social component to Google Bookmarks and integrates a lot of ways to share content online. It will be interesting to see if Google manages to build a community around the new service and if you can rely on it to find and disseminate what's cool on the web. Google will probably allow you to add the "Share" button to your site so you can replace all the bookmarking/sharing buttons for del.icio.us, Digg, Facebook etc. and provide a better experience to your users.
This is probably the first appearance of the Moka-Moka social project and Google will include shared information from other services (Picasa Web Albums, public events from your calendar, Google Reader's shared items or public Google Docs).
{ via Blogoscoped forum }