I know Jython converts Python code into Java byte code, but are there any syntax changes between the two? and as a side question is Jython 3.x usable yet or is it still being ported?
Jython is an implementation of the Python language. It is not a different language at all.
According to the Jython website, the latest stable version is currently 2.5.3b1, and the latest development version is 2.7a2. As far as I know, no one is currently working on an 3.x-compatible version of Jython.