When do you know that ESG (or factoring environmental, social, and governance issues into investment and corporate decisions) has gone mainstream? One clue is this week's announcement that MSCI (Morgan Stanley Capital International) is acquiring ESG research conglomerate RiskMetrics (which gobbled up ESG pioneers KLD, Innovest, and Institutional Shareholder Services over the past three years). Another is the agenda of last week's meeting of the Securities and Exchange Commission's Investor Advisory Committee (IAC), which included items such as "ESG Disclosure Work Plan" and " Proxy Voting Transparency ." So what does this mean?