If you blinked this summer, you might have missed the multiple updates released for the various functional programming languages. Scala, Clojure, F#, and Haskell all saw a great deal of progress over the past three months.
Scala has turned into a downright compelling choice for increasing velocity in Java development environments. F# could do the same for .NET shops, provided it finds its Twitter. It would seem that summer is a time to get stuff done in programming language circles.
PHP got a security release update in version 5.3.3 last week. And as the Linker pointed out, Rakudo looks to be quite stable, meaning Perl 6 has its soap box. Fortunately, Python's big jump to 3.0 happened last year, so not every platform is tectonically shifting beneath your feet this summer.
There are lots of new languages cropping up, though, so if you're looking to try out something weird, prescient, or powerful, take a look at Clay, Google's Go, and R. That last one isn't new, but as a statistical computing and graphics-focused programming language, I'm betting it's becoming more and more relevant to your needs every day.