So while some topics change radically (JAX-WS vs JAX-RPC) others change very little (e.g. XML, XML Schema, SOAP 1.1 (though 1.2 is added), WSDL 1.1, UDDI, JAXR, etc.). The big question is whether any of the old topics will be dropped and if any new ones will be added.
Since it will change, and some change is dramatic, such as JAX-WS vs. JAX-RPC, do you think it is worth take the current vertion of certificate, or prepare(such as learn JAX-WS) and wait until the new version is available?
You don't know what your situation will be when the exam finally does come out.
Preparation materials won't be immediately available - and if history repeats itself they'll be a long time coming.
There is the implied expectation that the next version will be easier because annotations in JAX-WS seem to make development easier. I challenge that expectation because there is no reason for exam to drop any of the non-Java web services material - it's just too much part of the web services development process. If anything it will become harder because the covered scope of the Java API could increase and more of the WS-* standards may become required knowledge.
If you visit the Sun CertManager and view Certification Progress, you'll see in the list a recently added SCJP 6 and an SCWCD 5, neither of which are available yet. I believe the Sun folks plan to focus their energy on those two exams before pursuing another SCDJWS, assuming they ever do.