I wasn't familiar with that library; will have to check it out.

I've had luck compiling wiringPi libraries using WolframLink. Granted, this is with the model B; however, the WiringPi libraries have been updated for B+ and therefore this method should be viable.

I can also toggle GPIO13 by echoing to the sysfs class files from the command line. But with the same setup, WL does not toggle the pin, either within "sudo wolfram" or withing wolfram executed under a "sudo -i" root user session.

We have not yet added support for this in the device functions (DeviceConfigure/DeviceRead/DeviceWrite), but this will be supported.

But it is possible to do this yourself as well, and it isn't very difficult.

Remember to launch the Wolfram Language as root (i.e.: sudo wolfram), because the GPIO modifications require root level access:

gpioExport[n_Integer] := Put[n, "/sys/class/gpio/export"]
gpioDirection[n_Integer, dir_] :=  Put[dir, "/sys/class/gpio/gpio" <> ToString[n] <> "/direction"]
gpioValue[n_Integer, val_] :=  Put[val, "/sys/class/gpio/gpio" <> ToString[n] <> "/value"]

And then, for example, this will turn on an LED if it is properly hooked up to GPIO13:

gpioExport[13]
gpioDirection[13,out]
gpioValue[13,1]