[stratospark]

Definitely learn Javascript, it's the language of client side web (becoming more popular on the server side with projects such as node.js). It only gets more interesting as browsers become more capable (local storage, WebGL, web workers, etc.)

As for PHP, it's definitely established as one of the most popular server side languages. You'll be able to find plenty of companies that could use PHP skills to maintain existing infrastructure. However, newer startups are more likely to be based on Ruby or Python, with the more adventurous exploring Clojure, Scala, node.js, etc.

With Clojure or Scala, you'd be able to leverage your existing Java skills, so that might be something to think about. I bet you'd enjoy the new programming paradigms these new languages offer. With PHP, you're not going to be learning many new concepts.

As for finding a job, you're just going to need to check the job postings in the areas you want to move to. You'll find a bunch of PHP like I said, but see what else people are looking for. Good luck!