James Robinson has a post of questionable truth up about Google removing search results for Vivint (a Nest competitor) from Google search. Now, Matt Cutts clears up that this was part of a SPAM thing and says it has nothing to do with the Nest acquisition.
This though will always be a problem. When search results are as important to finding good information as they have become, then there will always be questions around integrity for companies that run anything other than just a pure search engine. This is one of the reasons I like sites that are member supported, and why I like DuckDuckGo so very much.
Who knows what the truth here is, but that in itself is the real problem. We, as users, should never have to question if the search results are being refactored to better support the companies other products. With Google1 there has been a lot of smoke (and some clear instances) of the company gaming search results to better support their products.2
That simply shouldn’t be the case, search accuracy is far too important.