It is like annotated bookmarks/favorites you store online and share with your friends.
I have been using it for about a month and it is fun and easy to use once you install it. With the Dude toolbar on your browser, you can then bookmark or "dude" items you like by clicking a button. The window then splits in half and lets you decide if you want to send it to other users or just mark it for yourself. You can drag in non-linky pictures and you can type in snarky comments for friends.
You pick an avatar and a name for your blog (mine is called PonyUp) and start a page of your links with pictures, comments, etc. listed in chronological order.