Commodities have become attractive to investors again, although not for reasons of portfolio diversification. Of the several factors that have combined to make them appealing, one is simply a reflection of an old clichéd admonition.Commodities, commodity funds (of various kinds) and investors have had a checkered relationship the last 20 years or so. Managed pools of money devoted to trading commodities developed during the 1970s and 1980s as a critical mass of interest in commodity markets grew. They were styled along the lines of mutual funds for equities that have been around considerably longer, enabling those with relatively small amounts of capital to trade by investing in funds that pooled their money with that of others to be manage...