EXECUTE: Create default Seam 1.2 web project
EXECUTE: Open home.xhtml and make DnD of <a4j:commandButton> and <rich:calendar> from Palette
FAILURE: xmlns:rich="http://richfaces.org/rich"
xmlns:a4j="http://richfaces.org/a4j" will be inserted.

ASSERT: xmlns:a4j="https://ajax4jsf.dev.java.net/ajax"
xmlns:rich="http://richfaces.ajax4jsf.org/rich"

For Seam 2.0 and higher xmlns:rich="http://richfaces.org/rich" and xmlns:a4j="http://richfaces.org/a4j" will be right path.

ASSERT: Look at version of seam that is used for web project and insert proper taglib uri.