There are no prerequisites for the SCEA, either the old one or the new. The reason is Sun's thoughts on certification - their certs are arranged by job-role, and Architect is separate to them from Developer. Since none of their other certifications target the role of application designer, they don't have anything else that's required before the SCEA itself.
Theodore Jonathan Casser
SCJP/SCSNI/SCBCD/SCWCD/SCDJWS/SCMAD/SCEA/MCTS/MCPD... and so many more letters than you can shake a stick at!