CPN Tools is written in Beta, a object oriented language developed at Aarhus University and University of Oslo. The language is no longer actively maintained (though a variant, GBeta is getting more maintenance love). This means there is no way to reliably compile CPN Tools on Linux and Mac OS X.
We used to have a Linux version of CPN Tools, but the performance was never satisfactory. In fact, performance when running under a virtual machine was consistently better than when using the native version for Linux. As maintaining multi-platform versions is a huge hassle, we have opted to cease maintenance of the Linux version and not to even consider a OS X version.
The only way to bring CPN Tools to these platforms is a complete rewrite, which is not happening in the immediate future.
Instead, the simulator, which performs all the heavy lifting especially during state-space analysis, is fully cross-platform and works on Windows (XP, 7 and successfully tested on 8), OS X (10.4 and newer, Intel only) and Linux. The code is 32 bit but works with no problems on 64 bit versions of all operating systems. This is due to the simulator being written in SML/NJ, which is seeing sporadic updates only, and this does not at the moment include 64 bit support.
We recommend using one of the common virtualization solutions for running the GUI component of CPN Tools using either Windows XP or Windows 7. All development is performed using Parallels Desktop and Windows 7 on a Mac OS X laptop.