Just a nitpick. But is’nt it wrong to use momentarily instead of - in a moment ?
The usage of this word has become so popular, e.g.
1> We will be boarding momentarily - Airport Talk
2> You will be connected momentarily to an operator - Phone call to Customer Service.
So, is this usage now acceptable American English ? Who started this substitution ? and Who decides what is valid American English ?
Thanks
Heck, I ** hope**it hasn’t, but I suppose it will be interesting to find out. 
I’d certainly hate to hear a travel announcement suggesting that we will land “momentarily” in airport X - it does rather sound as if one would have to be very very fast in leaving the aeroplane.
I suppose so. I’ve never heard that “momentarily” was incorrect, and I’m often a stickler for such things.
The American English Speaking Public, of course. 
Whatever becomes common usage eventually becomes “correct.” Languages are nicely arbitrary like that.
Been there, had that experience. It was Delta BTW 
My 25-year old desk dictionary lists “at any moment” as definition #3. So the usage has been around for a while.
In one episode of the sitcom “Sports Night”, currently in early morning repeats on Comedy Central, this very bit (including the airport joke) is used as a running joke.
Just another instance of life, or at least this thread, of imitating art.
m-w.com lists this under ‘momentarily’,
"
1 : for a moment
2 archaic : INSTANTLY
3 : at any moment : in a moment
"
So apparently, momentarily does mean ‘in a moment’. I don’t really understand the problem, what did you think momentarily meant?
Well, jumping in from the eastern side of the Atlantic, I’d have to say momentarily means “for a moment”, as in to pause momentarily before doing something. Hence “we will be landing momentarily” does bring to mind images of passengers leaping from an aircraft as it briefly touches down on the runway…
But, the “in a moment” meaning does seem to be creeping in. [flamebait]I blame those language-mangling Americans.[/flamebait] 
Well, momentarily is the adverb form of momentary, which doesn’t seem to have the meaning of “imminent”. It means “lasting only for a moment” according to dictionary.com.
shuddering
I will go with h.sapiens’ definition.
…whereas taking off momentarily works, because you only want to be taking off for a brief moment… after that, you’re flying…
Boy, nobody pulled the usage note up yet? From AHD (at dictionary.com):
Why should momentarily be unacceptable to mean “in a moment”, but instantaneously be acceptable to mean “in an instant”?
While I will usually be proud to admit that we Americans have shamelessly manhandled one of your precious words, I don’t think we can take credit this time. According to the dictionary, momentarily = “instantly” is an archaic defintion.
Ah, but “instantaeously” means “in an instant” in the sense of “during a very short period of time”. Thus the Big Bang happened in an instant; it was an instanteous event; it happened instantaneously. It does not mean “in a very short time from now”. You would not say “the manager will be with you instantaneously”, meaning that the manager is going to arrive very soon.
As has been pointed out above, “momentarily” in British English means “for a short time”, but not “in a short time from now”. In American English, it can have either meaning, depending on the context, although obviously some American speakers dislike the “in a short time from now” usage. However I think “instantaneously” has only one meaning in both British English and American English; it means “for an instant”, but never “in an instant from now”.
In a hundred years, “momentarily” will be synonymous with “shortly” in exactly the same way “nauseous” is now synonymous with “nauseated,” and nobody will think twice about it.
“Penultimate” will be synonymous with “ultimate.”
“Orientate” will not be regarded as ignorant usage.
And so on. Language evolves, whether we like it or not. What we call “correct grammar” simply refers to how the majority of the population spoke the language yesterday.
I have heard - although not with my own ears, thankfully - that in UK English the word “momently” is used for “in a moment.”
If true, that is an abomination before God, Shakespeare, and the King James Bible.
“Orientate,” incidentally, is a word that has a much worse reputation with the general public than it does with language gurus. It’s accepted by virtually all dictionaries, for example. This includes the (original) Oxford English Dictionary, which traces its usage back 150 years.
It’s hard to get too worked up about the drift of “momentarily,” since there’s a plethora of other words and phrases that do the same work as the original meaning of “momentarily.”
This is so sad. Penultimate is my next-to-favorite word.
Ah. But will “antepenultimate” then be synonymous with “ultimate” or with “penultimate”? Or, indeed, will it still mean antepenultimate?
Note that “presently” went the opposite direction as the English language evolved. In Shakespeare’s day it meant “at once”.