It would be very interesting if Google bought Opera. Opera is a pretty sweet browser which I’ve always liked, and even paid for back before they went free (which, as it turns out, was partly due to Google).
Let the speculation begin on what might happen if they owned a browser. My hunch would be that it’s some kind of pre-emptive defense against IE. If all of the crazy theories are true that Google is setting it’s sights on being your Operating System, but in a browser – as long as 90% of the users out there are using a browser built by a company that has a vested interest in you buying their Operating System and not Google’s, that would be an extremely weak point in their strategy. Microsoft would still control what you can and can’t do.
With Opera you get a cross-platform, fast, mature, secure browser that is closed-source and proprietary (which may be an advantage). You can start building features on it via the same “embrace and extend” philosophy that Microsoft used with IE. It must kill Google to have to say “Google Desktop – requires Windows” or “Picasa – requires Windows and IE”. How much nicer it would be for them to say – here are all of our apps, Google Browser required, underlying OS – meaningless.