Microsoft have been working on
Wallop for some time, however recently it's been opened to a few testers (thanks to Barry from
Search Engine Roundtable for my invite) and I have recently been able to test it.

The main function of Wallop is to allow sharing of media between friends - friendship groups are all linked graphically. To get an idea of how groups are visually represented - take a look at Microsoft's
Social Computing Group page. Wallop is like Yahoo's recently talked about Yahoo 360 - also invitation only at present.
One of the most interesting features about Wallop is the interface - almost everything you click on (even drag over) is animated in some way. Although not obvious from the screenshot above the entire front-end is built in Flash and works quite well. There were numerous occasions where I right-clicked on items expecting more menus to pop-up like a standard application! It's not often I see interfaces like this in a browser and it does take a bit of getting used to.
Whether it'll take off or not it's an interesting service and worth a try, if you email me I should be able to give an invite if you're quick!