Google SearchWiki: Useful for who exactly?

Google has now launched the much talked about Google SearchWiki – a set of tools allowing Google account holders to add comments to specific Google results, move results up and down or remove them completely in order to customise search engine results specific to searcher needs.
Cedric Dupont, Google’s product manager told the BBC news website:

“The SearchWiki is about giving users more control over their search results and increasing user happiness.”

The video below explains this in simple terms:

The burning question is whether this is a useful set of social search tools for users or whether Google will be closely monitoring user behaviour and ranking sites accordingly.

I would imagine the first thing most SEO’ers or digital marketers will do is move their own or their customer websites to the top.

Over time, what kind of information is Google drawing from such user behaviour? If brands with great deals or superb customer service get moved to the top by loyal customers, will Google modify their rank on this basis even though their websites wouldn’t naturally rank high?

If the latter is the case, the whole system could be open to abuse in the same way that SEO’ers were able to improve PageRank through paid links.

The question begs: what are Google’s real motives? Increased market share of social search (not that there’s much competition!) and bookmarking services? Or yet another addition to their ranking algorithm by way of customer intelligence? If it is the latter, maybe this is another step in the direction of Google dominating semantic search otherwise referred to by some as web 3.0.