I'm studying for a Java certification. I haven't used Java since college, so it's a nice refresher. The one I'm after is SCJP. You basically study for a while and then pay $200 and take a test and you're done. You could take classes, I imagine, but they're optional and having looked at the material, I doubt they're necessary. I've started to study and the subject matter is not that advanced. Scoping rules and inheritance methods and some of Java's awkward syntax, for the most part. It's the kind of stuff you'd pick up anyways if you used Java for any extended period of time, which now that I think of it may be the whole point.
I'm not really sure a Java certification is "worth" anything. In any case I surely wouldn't consider someone whose ONLY qualification was this certification any kind of expert in Java; I likely wouldn't even consider them necessarily competent. But I think it's good to have the certification anyways, because 1) It shows I give a crap about programming enough that I'm willing to continue my education, 2) It shows I'm at least smart enough to study and pass a reasonably difficult exam, and 3) It MAY not help me in the future, but it surely can't HURT to have it on my resume. And it's only $200. Assuming I pass the first time.
After being immersed in Ruby for so long, Java feels cumbersome and awkward to me. There are so many artificial barriers built into the language. You can't test anything other than a boolean value in a if() expression. What kind of language doesn't make everything true by default? Ruby handles it so nicely; false and nil are "false", and everything else is "true". In Java you can't have anything other than an INT in the test conditions of a switch block. Why? I can't possibly imagine the motivation for that decision; I'm sure there was one, but it's beyond me. I know there are advantages to having a firmly structured language specification, and I'm not one to proclaim "OMG JAVA SUCKS" to the world as though I'm on a religious crusade; thankfully I retain that much sanity. But the advantages of a highly structured language just don't mesh with my personality, I guess. I find it tedious and constricting.
However if someone wants to pay me good money to write Java all day, I'll do it with a smile. I love programming. Any programming. Some kinds more than others, but any programming job is automatically better than every non-programming job, in my book. Even if I was writing QBASIC for a living I could be happy. Heck I'm fairly happy right now and I use Windows all day.