Is Google still considered a startup though? Sure they may compete in similar markets as startups - they're all 2.0 companies - but does 2.0 always mean startup?

Or can a company move on past that and become established without being bought out by some other big company?

Oh, and just food for a thought, does this definition make Yahoo a startup with MS trying to acquire them and their stake in web2.0 sits?

To avoid going too far off topic though, it seems like there's an ecosystem of programmers and exec's going between the major companies/startups for a few years at a time, how well does this work for innovation - do the same people do the same type of thing all the time with minor tweaks (albeit in different languages/forms), or do people largely try do things differently every time?

Do you mean Google is poaching from facebook? I've heard a lot about people going the other way, developers as well as execs.