1. button
2. gotten
3. mountain
4. eaten
5. wait
In all of these examples the t is dropped entirely in all but the most formal speech. Unless you mean something different this is not a new phenomenon and is actually a characteristic marker of American English. In fact everyone I know, even people 30-40 years older than me, drop their t's everywhere. It actually feels weird to me to pronounce them in the above example and it sounds like I am scolding someone. I don't really know the linguistic history of it and my family has only been here a few generations, but everyone back to my grandparents spoke this way. Perhaps it wasn't as common before the 30's though.
As for news and what-not I'm so used to it I didn't even notice any change in inflection. NPR tends to be very hip these days (unfortunately) and so I am not surprised they are speaking more casually than a normal newcaster.