Java is a must for Android development. If you are comfortable with C++, then picking up Java will be very easy, but if you've never programmed in an object oriented language before (e.g., Java or C++), then you will have a steep learning curve.
But, if you're just doing it for fun, then who cares? Download the SDK and start playing around with it. Your best resource to get started is
Android Developers. Start with the API demos, then look at the other sample apps.
Good luck!
Steve