The Apple Developer Connection (ADC) has posted a new series of articles for Windows developers looking to port their products to Mac OS X. The series is called "Porting to Mac OS X from Windows Win32 API," and offers a fairly thorough grounding on the topic. It also includes links to other resources available from the ADC. The introduction from the article:
Apple provides many programming resources for creating Mac OS X applications, and which one you choose depends upon your needs, preferences, and constraints. If you are unfamiliar with the Mac OS X platform, the process of choosing the right approach can be time-consuming and confusing.
The purpose of this Guide is to get you started porting an existing procedural Win32 application written in C or C++ to Mac OS X. You are, of course, encouraged to explore Appleis various APIs and choose the ones that best fit your needs.
You can find the article at Appleis ADC site.