I've made some progress with this. There are a couple of things that were (and still are) causing trouble
1) My WXWIN system variable was incorrect and pointed to a non-existent wxWidgets-2.9.4 directory. I'm not sure if I previously had installed then removed 2.9.4 or if wxWidgets-3.0.0 generates the wrong system variable. You can check it at the command prompt by entering
echo %WXWIN%
and if it is incorrect then use
setx WXWIN path\to\my\wxwidgets
which will permanently correct it. Note that capitalisation probably matters as CMAKE needs correct capitalisation for paths.
2) The patch I mentioned before is probably needed - I haven't tried without
3) CMAKE cannot find the 64 bit version of wxWidgets (which is what I was trying to build). Even worse, if you have both 32 bit and 64 bit wxWidgets libraries installed it will incorrectly find the 32 bit libraries for the 64 bit build, which I'm sure will cause huge, difficult to find linker problems later down the line.
My CMAKE isn't up to much, but I might be able to write a patch for the 64 bit problem and I'll pass this to CMAKE if I do, as well as publishing it on this list.
Once I have this all fixed I will edit the wiki

On Tuesday, 10 December 2013, 10:51, phil rosenberg <philip_rosenberg@yahoo.com> wrote:

I've just attempted my first build of Plplot with wxWidgets 3.0 too. This is on Windows and I can confirm that the latest version of CMake does not find the wxWidgets 3.0 install. In my case I only have 3.0 installed as this is on a fresh install of Windows 8 and the wxWidgets bindings are simply disabled due to not finding the libraries.
I found this bug report and patch http://www.cmake.org/Bug/bug_relationship_graph.php?bug_id=14587&graph=relation. But manually applying the changes to findwxWidgets.cmake doesn't seem to help. Unfortunately one of the replies in the bug report indicates that nobody is maintaining the wxWidgets module.
In response to Werner's post, wxWidgets 3.0 is incredibly simple to set up on Windows. The binary install creates a visual studio project which builds out of the box, with both 32 and 64 bit options. The only config change I made was to enable the wxPostscriptDC.