@Blue Ink:

We had a dominating rendering engine once, and it didn't turn out very well. Just say no.

We had a dominating proprietary rendering engine once. The proprietary thing is key.

Once you put total control of the direction of something universally important under one entity, that's that the key problem that leads to stagnation.

It makes bad politics and you know what it makes bad science and bad software too.

Again honestly if Microsoft wants to waste some of their best talent and significant money to duplicate lots and lots of work that is already been done and is completely available to them ... excellent!

Do you honestly think I'd even mention something I view as a significant inefficiency at Microsoft without any motive? Why in the world would I do that? If fixing CSS for IE wasn't so annoying I'd be cheering it on.

The fact is, it makes a lot of sense to adopt Webkit at least for mobile. That's what people tend to target. Microsoft is literally the sole outlier, and with their 2% marketshare (and Webkit with pretty much the rest) browser support is just not going to work out very well with them. They'd save money maintaining Trident, which can't be cheap, and they'd instantly have a rendering engine with more HTML5 support. I don't see how there is a disadvantage for Microsoft at all. It's win-win-win-win all around.

Google must think so, too, given how they are funding the development of Gecko.

No.. they are paying Mozilla for adding branded search to their browser, it has nothing to do with Gecko. It is quid-pro-quo.