The Microsoft spokesman was complaining about how people are just now catching up to what they were shipping in the last century.

That's because it is only now that there is the user base for it.

Even today before doing something that breaks Netscape 4 I think about the question. Even today I would not introduce a dependence on XMLHttpRequest in a website aimed at the general public because I don't want to lose the several percent of business that would shut people out.

If Microsoft produces a really great technology, then I'll think about it in 2010. After everyone else supports it and it has been well adopted. If it doesn't produce really big benefits over other approaches, I might wait a few more years than that.

(This doesn't just hold for Microsoft of course...)

Cheers,
Ben