Kelly Goetsch has written a very impressive 64 page guide on the development and deployment of very large scalable ATG e-Commerce applications. There’s a ton of great information (a little bit came from me!) and it’s a worth-while read, even if your application isn’t running on 200 production servers. Unfortunately you have to have an atg.com account AND be associated with an active support contract in order to read it.
If you do, check it out: https://community.atg.com/docs/DOC-1871
Obligitory Spark::red ATG Hosting plug: The three founders all worked on AT&T’s massive ATG e-Commerce cluster, so we understand how to scale ATG to hundreds of nodes, and how to squeeze out maximal performance and stability out of clusters of any size.