Carpe diem is the clarion cry of hospitals confidently leaping into the future to do business online. That industry trend has spurred the launch of Third Millennium Healthcare Systems. This new healthcare arm of the Internet solutions company Third Millennium Communications (3MC) in Atlanta joins a handful of newcomers pursuing the $10 billion "connectivity" market. Connectivity players provide specialized Internet solutions to connect a variety of healthcare participants: providers, patients, payers and suppliers. 3MC's direct competition is Healtheon Corp., an Internet technology firm in Santa Clara, Calif.