HUBweek in Boston. Denver Startup Week. The Tom Tom Summit & Festival in Charlottesville, Va. South by Southwest in Austin, Texas. These are just a few of the many highly successful and very well-attended entrepreneurship and innovation events now taking place across the country. Some of them go on for a few days, others for a whole week, as their names make clear, said Kristen Leutz, executive director of Springfield-based Valley Venture Mentors (VVM), who has been to Startup Week and will likely attend some of those other gatherings in the months and years to come as she seeks to learn more about entrepreneurship ecosystems, how they work, and how they can be developed and expanded.