It's absolutely regrettable. If this was legit, it would mean that the browser would be faster, the user experience would be better, and developers would be another tiny step closer to having an easier time of things when working in IE. I don't feel sorry for Microsoft here, but I'm a web developer, and I want fast, continually-improving browsers to code against.
The only thing they will regret is getting caught, much like any sociopath.