Win32::MemMap.

... and if you're looking to improve your searching-fu when it comes to Win32::* modules and other PPMs, try adding some of the more notable repositories to your config, so that all it takes is a ...

c:\> ppm
PPM interactive shell (2.1.5) - type 'help' for available commands.
PPM> search Win32-MemMap
Packages available from http://jenda.krynicky.cz/perl/:
Win32-MemMap [2.0.3] Shared memory between processes.

    --k.