I think it would be very handy if you could specify icon for each result, back to my example :
specific icon for each icon makes the choice easier... one for google, one for yahoo, one for live, etc.
but having a global icon for an alias is a good idea too, and i would use it ! maybe you could add a global icon which shows for every result of the alias but is ignored when one is specified in a result of the alias
Cheers, nitrix