I’ve had a lot of feedback with my article Exactly what is Alfresco?. A recurrent question I’ve received was where to find more info about WCM with Alfresco.
You can Download Alfresco Web Content Management 2.1 under Download Alfresco Community Network. There you can find Alfresco 2.1 Web Content Management Product Evaluation Guide which is a very complete guide about the WCM module.
Hope this helps.