OS X Mavericks has got the same requirements as Mountain Lion. Just open System Information or System Profiler app (in /Applications/Utilities) and check your model identifier. If it's iMac7,1 or a higher number, your computer is compatible.
We don't know anything more about OS X Mavericks, so you will have to wait until the final version is released to know if your computer will work properly. Note that this version includes a huge number of performance improvements and a better memory management, apart from OpenGL 4 compatibility and more. See > http://www.apple.com/osx/preview