What hardware / software do I need to port my C++/wxWidgets app to the MAC?

I have a C++/wxWidgets codebase and I'm starting to think about porting it across to Linux and the Mac OS X.

What hardware / software do I need (or is recommended) to code on the Mac platform? Currently I use Visual Studio to develop in and Innosetup to do my packaging.

The Mac equivalent of Visual Studio is Xcode (assuming you have a Mac :-), which includes the Mac port of gcc.

http://developer.apple.com/xcode/

For Mac development, the simplest and easiest solution is to use Xcode on Mac OS X.

You might be able to virtualize that on your Windows box, or install it as second OS depending on your hardware, but the path of least resistance is to develop with an actual Mac in front of you.

You can use IMCROSS to set up an environment for targeting Windows and MacOS X from Linux.