Bertrand talks about Atlas and browser compat
I've seen a few mentions of how well the toolkit stuff does (or doesn't) work in Safari. We chose to focus on IE and Firefox for our first release, not only for resource reasons (there's just three of us!) but because of some of the reasons mentioned in Bertrand's blog. What we can make work in Safari (especially as Atlas support continues to improve, they're not even beta yet!), we will.