The official LEGO Mindstorms NXT FAQ has been updated with a few questions pertaining to the HiTechnic Compass Sensor. The last question asks, “How do you program the Compass Sensor?”
There will be a patch available by the end of October that will enable 3rd party programming blocks in the MINDSTORMS NXT environment. In the meantime, the current version of MINDSTRORMS [sic] NXT software will allow the Ultrasonic block to program the Compass Sensor.
The ‘patch’ has been rumoured for quite sometime now, but this gives us an indication as to when we can expect it. The end of October draws near and we will probably see a download available for the Compass Sensor block as the patch goes live.