Where 'x.y' is the version number. This will create a subdirectory called gpsim-0.x.y . All of gpsim's source code will be untarred to here. Here's the beginning of gpsim.ps and gpsim.pdf , the gpsim documentation. Or if you perfer, here's the Lyx source gpsim.lyx .
Modules gpsim supports loadable modules.
This means that it'll now be possible to add devices to gpsim that are in fact totally separate from gpsim. This is the very first one and is still somewhat experimental. Here's a screen shot of the 7-segment display in action. There are no graphics to show. This library also illustrates how a module can drive a pin on the pic.