> ok, it does indeed blink, but what is the purpose? Accept for the fact that
> now I can't tell by looking at the led whether the machine is down or not.

That's roughly it, although the blink rate varies according to load.

According to /usr/src/sys/arch/sparc/sparc/auxreg.c:

        /*
         * Blink rate is:
         *      full cycle every second if completely idle (loadav = 0)
         *      full cycle every 2 seconds if loadav = 1
         *      full cycle every 3 seconds if loadav = 2
         * etc.
         */

Cheers,
Rob