It appears many of the current ranking signals point to link profiles and domain authority as being of the most importance, among other things like social presence, overall quality of content, etc. It appears that +1's, shares, etc, when intermixed with a strong diverse link profile, can have good effects on ranking in SERPS. However, it doesn't appear that social signals alone carry as much weight. Its really a combination of factors that will determine your ranking outcome. For now, ranking remains tight in the hands of major publishers, but this doesn't mean you cannot rank.