Yes, we do have documentation for ECF 4.0. Here are some links --
http://www.mediachase.com/documentation/ecfv4doc/ecf4_Getting_Started_Install.pdf
http://www.mediachase.com/documentation/ecfv4doc/ecf4_commerce_manager.pdf
http://www.mediachase.com/documentation/ecfv4doc/ecf4_rps_dev_tutorial.pdf
http://www.mediachase.com/documentation/ecfv4doc/ecf4_site_structure.pdf
http://www.mediachase.com/documentation/ecfv4doc/ecf4_localization.pdf
http://www.mediachase.com/documentation/ecfv4doc/ecf4_db_orthogonal_tiled.pdf
http://www.mediachase.com/documentation/ecfv4doc/ecf4_db_circular_tiled.pdf
http://www.mediachase.com/documentation/ecfv4doc/ecf4_db_hierarchical_tiled.pdf
Mediachase Software