I have seti running all the time, and just looked over and saw the icons'
turned gray. It was red just a few minutes ago, so I updated. 

1 How many more icon colors can I expect ?
2 is there a legend on what the colors mean ?

I'm guessing this gray one means that it's recognized the cpu is under heavy
usage and has auto put itself on some sort of monitor for more when power is
available. 

It's already set to use CPU 1 instead of both, and low priority usage.
hovering over the icon doesn't really say much more than I already know, that
it's seti that's running.
more pix @ http://members.toast.net/cbminfo/index.html