Kevin Rose, of Digg and Revision 3 fame, just launched an invite-only alpha of his latest project, Pownce. Pownce lets you share files, links, and other info with your friends. It's not an original concept. Yet Pownce makes an extremely good first impression. (Earlier, we had invites to give out--but we're sorry, they're all gone now.)
Pownce strongly reminds me of Tubes (review) and Izimi (review), and little less so of AllPeers (stories) and Pando (quick hit). It's also reminiscent of the file-transfer feature of various instant-messaging clients.
There's also a heavy dose of Twitter (stories) in Pownce. Every time you send a file or note, it's added to your running feed of activities that anyone can view; likewise, it's easy to see the public feeds of other users and the private items posted by your friends.
You can send items to individuals on your list, to everyone, or to groups you set up (for example, you can have a family group, a group for a project at work, and so on).
At the moment, Pownce lets you send plain text notes, URLs, files, and event invitations (and it tracks RSVPs). I would not be surprised to see audio or video recording functions built into the product, which would make Pownce an interesting alternative to Twittergram.
Pownce works through a Web page, and there's also a slick Adobe AIR (formerly Apollo) desktop app.
It's easy to discount Pownce as a me-too concept. In fact, it's several. But it's extremely well put-together--capable yet easy to get into and use. And useful. And fun. Try it if you can.