For some reason I used regular egg whites in a butter icing recipe.  Hate to chuck it.  Will it be ok?

As long as you keep the cake (and all icing - used & unused) in the frig. it should be o.k. for up to 3 days.

That what I always use for SMBC.

Regular egg whites as opposed to what? Most meringue buttercreams use egg whites. 

i'm gonna guess regular as opposed to pasteurized -- but it's just a guess

wendy -- if you are not able to reply here -- please feel feel to post your reply in a new post-- it's some kind of fluke in the program here that new folks can't repost for some time -- happens to everyone --

y'know -- just say in the new post that you couldn't reply in the original and then whatever you want to say