To me it makes perfect sense. For many people, web browsers have very little to differentiate them. Chrome's single major differentiator is that it's fast. If you asked the average person what's different about Chrome— they probably wouldn't care so much about the robustness of the html5 or css3 support— they'd say that it's fast.

Microsoft can attack on that front very aggressively. So they're taking the one thing that most people know is different or special about Chrome, and saying, 'IE is faster. Faster canvas, faster svg.' Seems like a great strategy to me.