Brian Steinberg Senior TV EditorNBC News already produces dozens of hours each day for MSNBC and programs like “Today.’ But it’s preparing to come up with a few more.The NBCUniversal unit is this week launching two new hours on its live-streaming service, NBC News Now, a testament to growing demand for news delivered quickly via broadband. Starting today, Aaron Gilchrist, formerly an anchor for WRC, NBC’s Washington, DC, station, will preside over a noon to 2 p.m.