Possible Duplicates:
Which programming languages can I use on Android Dalvik?
Which programming languages can be used to develop in Android?
What programming languages can one use to develop Android applications?
Also are there plans in the future to expand the amount of programming languages that Android will support?
UPDATE: There are really good answers over here
Here's a list of languages that can be used to develop on android:
Java - primary android development language
C++ - NDK for libraries, not apps
Python, bash, et. al. - Via the Scripting Environment
As for your second question: android is highly dependent on it's java architecture, I find it unlikely that there will be other primary development languages available any time soon. However, there's no particular reason why someone couldn't implement another language in Java (something like Jython) and use that. However, that surely won't be easier or as performant as just writing the code in Java.