This is a service designed for small businesses. It uses SharePoint as a large part of the service. From that Access perspective, I think this is a great thing for Access 12. As you know, Access 12 has many rich integration features with SharePoint. Looking forward, I believe many Office Live users will use Access as a rich frontend with link tables to their data stored in the Office live service. This should offer a great opportunity for Access developers as small businesses need more business app functionality than what is provided by the service. The SharePoint data should look just like a regular link table even though it is connecting to a web service.

Here is the signup link.

http://www.microsoft.com/office/officelive/default.mspx

Enjoy!