Safari's implementation is much less painful, is only triggered when I really want it, and provides sufficient visual clues about what's going on.
Chrome's blunder is almost enough for me to switch to Safari, which is saying a lot given my preference for Chrome otherwise.
Safaris implementation makes it very clear you are going to navigate back a page, and it's very easy for the user to cancel the action.
* I'd scroll something horizontally,
* I'd reach the edge of the page
* Chrome would render the "I'm about to go back a page" arrow
* Nothing I tried would cancel the "Back" action
Overuse of POST should help, though, as it lets the browser jump in to rescue you with a popup before you go Back.
Chrome is terrible compared to safari - the notification to the user is a very small barely visible arrow that gains visibility as the user scrolls further sideways.
Firefox is terrible compared to chrome, it just happens.
So as I said - Safari does something great, others copy it poorly, and "Lion breaks the web".
It’s a bug in Firefox and Chrome, nothing else.