Looking back at gameplay video, it doesn't look like I can see noticeable differences in the flashing characters have when getting up on the stage (looking for invincibility). Not that I can count frame all that well per se, but I'll let you guys be the judge. Though, as I'm writing this, I can't tell if Sakurai is referring to invincibility while using a getup attack or invincibility when actually grabbing the ledge.
As for the picture displayed, I think it's pretty clear that the position and trajectory Mario is in indicates that he was on the ledge, then Link Up-B'd him and snapped to the ledge. Regarding ledge-snapping; an example of how "strong" ledge snapping mechanics work is shown here at 5:39:
http://www.youtube.com/watch?v=cT4xjd9bGI0
You can hear Mario attempting an Up-b just at the edge, and then he's auto-snapped. From the looks of it, it's not nearly as strong as Brawl's auto snapping.
But look again at 4:41 in the same video. Mario tries to use cape literally at the ledge but falls through. Perhaps this means that recovery moves will snap but other moves won't?
Another example at 1:13. It's kind of hard to tell how the invincibility differs. I'm not sure I can make sense of it. But it's there.
I'd have to guess that lower % = less invincibility and vice-versa, at least that's the case if they're trying to nerf edge-hogging and edge guarding.
It's about time we got some new mechanic information, though.
