According to the service manual, this light can indicate that the fuse has been blown by the self-test to prevent deployment. This happens when one of the sensors has developed a fault and is indicating that the bag should deploy while the self test is in progress.
The system normally needs two sensors to indicate that the bag should deploy before deployment can occur. The fuse is blown by the self test to stop accidental deployment. If one sensor has gone faulty and indicates that the bag should deploy, you would be left in the dangerous situation of only one sensor being required to deploy the bag. This is not a good look, and so the computer blows the fuse. (The service manual says this much more clearly than I have, but I don't have it with me..)
The important thing to note is that if the air bag light stays on, your airbag WILL NOT deploy, even in an accident!!