Note: if you're configured your RPi to output through the touchscreen, and you disconnect the touchscreen (when the RPi is powered off, of course), then after rebooting the RPi may still try to output through the nonexistent screen. This bug is not yet understood and seems to be a kernel issue. But you can still follow the directions above to revert to HDMI output.
Touchscreen input (using the PiTFT) seems not to work by now.
== Building b2g for RPi ==