Like I say, ppm just breaks

That's interesting. I installed that ppm onto one of my perls - but I was using the PPM that's on CPAN, not ActiveState's PPM utility. Try using this as your ppd file instead: 
<SOFTPKG NAME="OpenGL" VERSION="0,56,04,0">
    <TITLE>OpenGL</TITLE>
    <ABSTRACT>Perl binding for OpenGL</ABSTRACT>
    <AUTHOR>Bob "grafman" Free</AUTHOR>
    <IMPLEMENTATION>
        <OS NAME="MSWin32" />
        <ARCHITECTURE NAME="MSWin32-x86-multi-thread-5.8" />
        <CODEBASE HREF="http://graphcomp.com/opengl/ppm58/OpenGL-0.56_
+04.tar.gz" />
        <PROVIDE NAME="OpenGL" VERSION="0.56_04" />
    </IMPLEMENTATION>
</SOFTPKG>

[download]
It contains <PROVIDE NAME>, the absence of which may (or may not) be the cause of the problem you're having.

Update: Hmmm ... I don't think that will help. I just tried installing via (ActiveState's) ppm on ActivePerl build 822 and it worked fine for me. I used the same command (and hence PPD file as you did): 
ppm install http://graphcomp.com/opengl/ppm58/OpenGL.ppd

[download]
Cheers,
Rob

In reply to Re^6: Win32 - gl/glu.h problem by syphilis
in thread Daunting Problem With Perl Opengl Lighting by iSina

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