I recently started creating applications for mobile devices and have successfully completed an application for the iPhone. I am now turning my attention to the Blackberry bu
Even though certain components of the RIM development platform are java-based, such as the JDE - other components such as the preverifier and device simulators are implemented as native Windows executables.
Basically, the easiest way to do it is to install Windows on your Mac using Bootcamp or Parallels and run inside a real Windows environment on your Mac.
However, there are other "hackier" ways to do it using Wine, MacPorts, and a number of other tools - as an example see this blog post