P.S. Here's a quick cameraphone photo of one of the prototype RS-232 modules.
For production we're using a blue GoPort header...and we made the PCB a little bit wider. Otherwise this is identical to the production units.
The GoBus 1.5 for STM8S draft firmware is SPI-based, so you can plug up to eight of these directly into your Netduino Go.
P.P.S. The RS-232 module and the XBee Adapter module use the same firmware base. Since they're so similar, we're getting the XBee Adapter module ready for production next...then the Ambient Light (I2C) module.