In case you guys missed it, we (Google) released our Native Client project. This project was created to allow the execution of native code inside a browser (for obvious reasons, it only works with x86 platforms). The reason I bring it up is that it can also be ran as an stand-alone container for applications so this can be used to create multi-OS applications that runs unmodified under any supported OS. For example, SDL Quake was ported to it and the required modifications were very small. The new Quake executable runs equally well under Linux, Windows and MacOS (all supported platforms).
Maybe this could be something good to bring to Haiku? I would be willing to work on the specific Haiku port but the build system requires scons and I am not very motivated to port this. :) Anyway up to the task of porting scons to Haiku? Maybe this could be a candidate for a HaikuPorts project?
Anyway, more information here: http://code.google.com/p/nativeclient/ -Bruno