I am noticing an increase in the hard glottal stop in the pronunciation of mitten and kitten, now more like mih'in and kih'in. Soft glottal stops are already common in fountain, button, apartment. (The purported increase in words like bottle or butter are actually voicings instead, turning them into "boddle" and "budder.") I don't know if this is national or regional. Here's the odd part. It seems much more common not only among young people, where one would expect change to be more prominent, but among young women. I may just notice it because my daughter-in-law is one, and the young woman I have worked most closely with the last five years is another.
Here's a fun article about Language Myths, BTW. I will no longer fight to remember to say "It is I." It's me is just fine.