The Honolulu Star-Bulletin reported today on a brand new gas vent at the Halema`uma`u crater at the Kilauea volcano on the island of Hawaii. This gas vent, also known as a solfatara or fumerole, has emitted a large amount of sulfur dioxide, sulfur trioxide, and water vapor over the last few days to the point where health warnings and closures have been issued for the area around Kilauea. Also in the last few days, dull red glowing material has been visible near these vents. The temperature of this material is only 772 K, which might be indicative of molten sulfur.
Solfataras might be a good terrestrial analog for Io's Prometheus-type plumes. These plumes are thought to be formed when silicate lava interacts with sulfur dioxide frost on the surface.
Link: Glowing sulfur stumps brains at volcano site [starbulletin.com]