UPDATE: All invites are gone, I'll update this post if more come available

What's MyWallop.com you ask?  Here's the blurb from their website:

Welcome to Wallop, where you can share photos, blog, and interact with your friends.

Wallop is a research project of the Social Computing Group at Microsoft Research, exploring how people share media and build conversations in the context of social networks. We are currently conducting a small, real world trial of Wallop with small friendship groups. Therefore, membership in Wallop is limited to study participants until the trial is over.

And from my beta invite:

About Wallop:  Wallop is designed to allow you to communicate in a more open and lightweight way with the people already close to you. It is unlike other social network software in that the primary focus is on creating interesting content and communication among a known set of people, not on browsing large networks to find people you already know or discuss general topics of interest. However, you are allowed to browse across networks, so keep in mind that content you create is accessible to others in the system.

Wallop & Email:  This version of Wallop works primarily over email. You will receive replies to your posts and media directly through email at any address you choose, and can reply back directly from email to make threads. You can create content in Wallop through the web client, through an external blog that you already maintain (if it has RSS syndication), through email (we accept photos and mp3s from your email attachments just as if you uploaded them), or from an XP desktop via a simple uploading tool you can get from the help section.

Inviting Others:  By inviting someone you know, you can view the content that they share in their network, both in the web client and in a digest we send to you twice a week. By default their network activity is visible to you and vice versa, but either of you can choose to add or exclude people as you see fit.

If anyone is a member over at Orkut or LinkedIn then you get the idea.  It's basically social networking.  I got myself an invite to join their beta program and have a limited number of invites that I can pass along.  If anyone is interested, let me know by emailing me at joepruitt@gmail.com with a subject of “wallop invite please” and I'll add you until my quota is full.

The one thing I have to say about their site is the UI is VERY COOL.  A really great user experience that can't really be expressed in words.