The USDA released a new Plant Hardiness Zone Map for the United States for the first time since 1990. It looks like we're getting warmer in general, most areas are jumping up a half zone. The map is the standard by which gardeners can determine which plants are most likely to thrive at a location. It's based on the average annual minimum winter temperature.
I'm just north of Pittsburgh and now I'm officially zone 6b, meaning a whole new palette of plants should thrive in my climate.