I first noticed this on Android. Dolphin Browser has done this for years now. Swipe to the left side (by swiping right) to get to bookmarks, etc. Swipe to the right side to get to add ons.
Hopefully, Apple hasn't already patented this gesture.
The only phone I can think of that doesn't have that is the Nexus.
Interestingly, the button that HAS died is the search button. Any device I've seen with a physical home button has opted for a long press to be the app switch, and then to leave the menu button in.
Personally, I like the menu button. It feels very natural on my SGSIII (and also did on my SGSI and Galaxy Tab). It feels weird to hunt for the soft menu button (either top or bottom) on my Nexus 7.
Still getting used to it, but my initial impression is that it's a pretty slick interface.