Kin: I found Mac's equivalent, it's "Cmd-[".
Funny, if I use that keyboard command, it doesn't register that I have viewed the post until I go back to the main index (or reply to the post).... only then is the post no longer highlighted. Anyhoo, that does "sort of" do the trick... using it to see the previous/next post does take me back to the section index but I still have to select the next post in order to see it! Whereas within the post all I have to do is select previous/next. I guess it's an activity trade-off since it gives my fingers a break from scrolling (hahaha).
It will be used by me elsewhere that's for sure. Great tip... Thanks!