Recently the mayor of Boston, Thomas Menino, made a major step forward for urban transportation by proposing that all off the city’s taxis be replaced with hybrids by 2015! The progressive measure will significantly cut the city’s carbon emissions, and officials expect that within two years, 50% of the city’s 5,500 cabs will have been replaced.  Boston’s bold initiative situates it alongside San Francisco and New York, which have established similar efforts to green their taxi fleet by 2012.