The SenchaCon video on "Advanced Server Integration with Data and Direct" lists several links at the end of the presentation. 3 of the 4 links are no longer valid!

Direct Specification
http://www.sencha.com/products/js/direct.php

Ext.Direct
http://www.sencha.com/products/direct/

Ext.Direct Pack
http://www.sencha.com/products/js/download.php