This post isn't about a problem, it's about a solution looking for a problem :-)
After banging my head trying to get MM session management working in Win32, I realized that it's not built into the binaries downloaded from PHP.net. I have a replacement "mod_mm.c" file that seems to work with IIS; I'm not sure about it working for Apache, as it doesn't use shared memory: Is Apache multiprocess in Win32? Anyway, it works for IIS4, yet YMMV...
If anyone wants the code - or if anyone can suggest a good place to submit it - I'd love to hear from you.
-Walter