The SCWCD 1.4 version is the 'newest' (released in May 2004), and since the changes to Java EE 5 are only minor (the most major change is the addition of JavaServer Faces), there is no new SCWCD 1.5/5 exam. You would therefore be sensible to prepare for and take the 310-081 (or 310-082 upgrade) exam now. The next exam might be another 2-3 years yet, depending on the contents of the next Java EE release.
Charles Lyons (SCJP 1.4, April 2003; SCJP 5, Dec 2006; SCWCD 1.4b, April 2004)
Author of OCEJWCD Study Companion for Oracle Exam 1Z0-899 (ISBN 0955160340 / AmazonAmazon UK )