Pownce comes to fill the blank space left by the already crowed social network services and allows its users to communicate thru a cross platform Rich Internet Application (implemented using Adobe AIR, formerly known as Apollo) that empowers people to post messages, links, events and files to their friends or in a privately manner to just a few... this is just like what everybody would have loved Twitter to be... at least this is how I feel about it.
On their own words
Pownce is a great way to send stuff to people you know. Add friends, then send them big files, invite them to upcoming events, share great links, and whip off a note to anyone, everyone, or just a few people.News around the web have given plenty of coverage including Ryan Stewart, Tech Chrunch, Mashable, Center Networks (this guys even have put up a video of it) and of course even Mr. Scoble had something to say about it. So go check them out.