Re: Google and media in Australia, remember that there was that thing about their media asking for legislation there for 'fair' spidering of news-sites, so there might be some connection in choosing the area to experiment with. Though it is known they tweak things all the time (whatever the purity of motive), and you could easily point to the tweaks that point any which way as indicating corporate 'interference' when they probably are comparing against slight nudges in the alternate directions. The experiments are not a problem, the possibility that it becomes a globally directed policy may be (if it doesn't support your needs, or if it does support your biases).
I remember back to that case where, I think, one Orkney Islands newspaper site allegedly populated itself with news directly (but unclearly) scraped from another. Google doesn't do that. Partially curating what to sample is no more than what other bubbles of information do anyway, even given Google's scale. Google knows I reference the BBC news site more than average[1], I think, so may already skew me there - and if I remember a story on there from last year or sometimes yesterday it's easier to find via a Google search (without ever asking for a particular source) than via the Beeb's own search field. But it is also giving me very disperate sources that match, so it's far less of a bubble than without. And I can be critical about the technological/algorithmical limitations too, I think.
((Ah, I've been multiple-ninjaed on this, it looks like.))
[1] You may argue this is a bias of my own choice or circumstance.