I signed up for this yesterday and hope to get my invite here shortly.  ClearContext is attacking the "email problem" and I look forward to comparing and contrasting with my Xobni experience.  Here's their blog.  Speaking of Xobni, I finally got back up and running after fixing my "Cached Exchange Mode" issue.

So, I am back on track as a Xobni user and have 10 beta invites if anyone is interested.  They really nailed the beta program process and I congratulate them on the continued buzz they are building out there.  Lots of pain in the inbox and email is something everyone loves to hate. 

We'll see if my MS Outlook client can handle another plug-in as I love to tinker with new tools as they become available.  I have a few plug-ins loaded plus a Salesforce.com plug-in that makes Outlook jump through some hoops as it starts and operates.  Makes you wonder if the path to fixing this problem is through MS Outlook as the more I seem to load into it, the grumpier it gets.

Anyway, I'll keep you posted as I get my ClearContext access.  Here's a nice video tour that they made available for distribution (nice touch!):