Well, you can access Office Live web services, but not create your own. Click here for a list of the Web Services that Office Live provides.
The endpoint or URL of the web service depends what Office Live bizapp or workspace you are trying to connect to. Just navigate to the Bizapp in question and look at the URL in the browser. Copy and paste the root of the URL and tack on the web service portion
at the end.
Each Bizapp is it’s own subweb, so most of the URLs in question will look something like this:
Just to clarify - the Blogs/RSS/Wikis functionality shown in this interview is in
Windows SharePoint Services v3 - part of Windows Server System. WSS v3 will ship in the Office 2007 timeline, in the second half of this year.