EJB 3 was not part of the J2EE spec so that the reason for the caveat. The faq page probably needs updated for JEE 5 which does include EJB 3.
As far as I know, you should be able to run on any JEE 5 app server. Check you app server's documentation.
Seam 2.0.x from head branch works fine with GlassFish V2 for most stuff I have tried soo far.