What's happening with AJAX itself is it's catching on like wildfire at the grass roots.
There is an explosion in the use of browsers on mobile devices. This is a huge, basically untapped market, and the field is wide open right now. Opera has been working on this technology, and I think they have an opportunity there.
I'm impressed with what they've been doing. But I think the experience still is unsatisfactory. It's a little like the proverbial dancing dog it's impressive that it can dance, but if you want a real dancing partner, you have to look somewhere else.
Microsoft has cleaned up its development process overall by emphasizing security threat analysis and reducing the attack surface in their code. They have made progress, so I am not surprised that there is less likely to be vulnerabilities in IE than in any other browser.