At school we used to be told that human nature had caused a change in the meaning of the word "presently".
Where once it meant now, in the present moment, it had come to mean later, soon; procrastination is ingrained in us, it seems. The American import, "momentarily", seems to be taking the English word, meaning for a moment or a very short time, in another direction, however.
When used to mean in a moment, any moment now, it is developing a completely different sense of urgency. "Now" is our simplest time word to signify this very moment, but in the sense of "at this moment and for the foreseeable future" it is usually replaced by "today" - as in "Today there are fewer churchgoers than there were 100 years ago" - or "currently". But isn't "currently" almost always redundant? Removing it from a sentence scarcely ever makes much difference, just as in the phrase "past history", the word "past" can't possibly have a useful role. When else was history?
Some of the phrases describing time can be craftily used to save it. How often have you heard a politician say: "at the end of the day", "at this moment in time" (would that be now, Minister?) while mentally organising the rest of an answer during an interview?
Meanwhile, the American shorthand for something that goes on without a break, "247", seems rather useful - as in "He never had a minute's relaxation; he was on call 247". It has gained currency on this side of the Atlantic since we got used to the American version of September 11 - "911" - just another tiny ripple resulting from last autumn's terrorist attacks in New York.
Please keep contributing your observations. I will quote from them before the end of term.