I've just posted three brand new Office Live Screencasts.  Albert Shen, a software design engineer on the Office Live team recorded them and did a fantastic job showing how to use SharePoint Designer 2007 to customize the Office Live environment. 

Here are direct links to the screencasts:

1. Office Live with SharePoint Designer

2. Using the Data Form Web part in Office Live

3. Office Live Workflows

By the way - the Office+Live tag on Channel 9 gets you to all the latest Office Live content.

These are good ones!