Corporations are the main cause of the improper use of “momentarily.” To understand that, all you have to do is to call one of them. More likely than not you will hear an automated voice response such as this one.
“We are sorry that all representatives are busy at this time. Someone will be with you momentarily.”
What they really should be saying is “in a moment.” This is because “momentarily” means “for a moment,” at least in my mind. Those who disagree argue that there is no ambiguity when using this adverb in this instance because its meaning is easily derived from the context.
Which side are you on?