Not much I suspect but mostly foreigners were killed which means that we are targets whereever we go.
I'm really puzzled by your statement.
By the same token, why should we care about those killed at Beslan? or any other senseless act in any other country in the world?
"After much thought and consideration I have decided that this merits a big so what?"
Well, for one it is a visible set back for Mubarrak, who in the old language of Patton, may be a son of a bitch but he is OUR son of bitch and no friend of radical islam. Mubarrak leads the most progressive Egypt any of us could dare hope for given the strength of the nutter fringe out there and anything that undermines him is bad for us. Then there is the question of humanity. More people blown to pieces in the name of some twisted religion - it is a reminder to us all that there is no room for complacency in the face of people who think this way. I suspect there will be a number of westerners caught up in it (if not I suspect some Israeli's). So, that's my 'so what'!
Does it impact the 'average american'? Nope. Maybe not. But then neither did Germany's invasion of Poland.
If nothing else, the enemy of our enemy, at least might be, temporarily, our friend, or at least a useful ally. The Jihadies seem intent on making lots of enemies.