Chris Beard, writing at the Mozilla blog:
Microsoft is officially giving up on an independent shared platform for the internet. By adopting Chromium, Microsoft hands over control of even more of online life to Google.
We compete with Google not because it’s a good business opportunity. We compete with Google because the health of the internet and online life depend on competition and choice.
There’s a minority of people who are concerned about Microsoft’s announcement. Everyone web developer I know who actually has to comply with browser standards is very happy to hear it though. In a perfect world, there would be one open source browser with 100% market share.