Today marks a milestone on the nation's long march toward universal health coverage: the launch of online marketplaces, called exchanges, designed to help people find insurance they can afford. It's an idea by Massachusetts seven years ago. People here call their program a success, and say the state's exchange was an indispensable factor. Those involved since the beginning say the Massachusetts health insurance exchange, called the Connector, was the brainchild of former Gov. Mitt Romney, a Republican. Glen Shor, who once ran the Connector and is now the state's secretary of administration and finance, is confident that the nation will follow Massachusetts' lead.