I don't recall this being the case previous to 10.0.6/07, but maybe I've just never noticed it... Say you have a stack of, in my case, 5 connected clips above the primary for a composite or something. Now, using the KB, nudge any clip out of the stack. The stack drops and the clip drops to connect to the primary. Move it anywhere, but don't drag it, use KB shortcuts.. Now, nudge it back towards the pile, and it pops right back to whatever position it was in. As soon as you drag it with mouse, or trackpad, it forgets where it was and goes to the bottom of the pile.
This actually would have been good to know a couple projects ago for me... Anyway... not earth shattering, but kind of cool. :-) Anyone else notice this? Maybe it's always been so and i just never knew it...
You'll also notice that if that stack was rendered, it becomes unrendered when the clip leaves the stack. But put it back where it was and instantly rendered again. Take that legacy!
The mouse thing makes sense, because its the tip of the arrow pointer that determines exactly where in the stack you're putting the clip. But don't know if the nudge behavior was always there. Probably.