I know there are arguments against certification, and I definitely think that using certifiction to determine whether to interview or recruit people is downright daft, because frankly learning a bunch of answers isn't all that difficult. But I personally find that completing a certification really helps to round out my knowledge in an area. I guess my thoughts are that a fairly recent certification combined with the work experience to back it up is something that would make your CV more interesting to recruiters.
As someone who has worked more on web apps than "core" Java applications, I found the 1.5 SCJP dead useful for drumming into me the facts about threading etc that I don't usually think too much about. Plus since I did it very shortly after 1.5 started being used in anger, it was a good way to get familiar with the new features. Although honestly it could've banged on a bit less about Generics, the stuff that was in the exam I have never used in real life. Well, maybe once, and even then I looked it up on the internet to remember how it worked.
I'm doing the SCWCD now, I figured I might as well "prove" I can do all the stuff I've been doing for close on a decade now (if you count the fumblings of my third year project as web development). It's full of what Rands calls Holy Shit moments. Now, don't get me wrong, I'm a damned good web developer (no, really, it's true!!) but reading the book, having it explain some of the things I always took for granted, or stuff I ALWAYS have to look up because I can never remember exactly how it works, is filling in a lot of gaps. It also explained to me WHY I never really worry too much about thread safety - I'm already unconciously designing for it and more, by coding in as stateless a fasion as I can, something you really have to try to do in web development.
It feels like it will make me a better web developer, even if it is banging on about some of the Ancient (un)Holy Ways of JSP & Servlets which has been almost entirely replaced with using frameworks like Spring MVC or Struts (to their credit, although the authors have to teach The Old Ways they do keep pointing out this is not the way to do things these days). In fact, in a few simple sentences, they explained to me why I was having a recurring nasty problem on the last web app I worked on, which I was blaming on Sitemesh. Poor Sitemesh, how I have maligned you - it was not your fault at all, it was my abuse of the <jsp:include> tag (although frankly the fact that I HAD to use a <jsp:include> tag in the first place should probably have told me that I wasn't using the correct tool for the job, Sitemesh really is not a lightweight Tiles and clearly should not be used as such).
It's at times like these that I realise what my real skill is - cramming my brain with as much pertinent information as possible for short-term retention, and recalling it in high pressure environments. It's why my GCSE results are so great. It's probably also what makes me good consultant material.
Sometimes the information even sticks in there. Just ask me how oxbow lakes are created and I'll prove it.