There's a big sunspot on the surface of our nearest star right now. These are regions of intense magnetic activity, and can be the source of such explosive events as solar flares (eruptions of material off the surface when magnetic field lines get tangled up together and suddenly snap) and coronal mass ejections (huge eruptions of material from the Sun's corona).
Well, Sunspot 930 does not disappoint. It had an eruption the other day, but it was pointed away from us. Today, however, it launched a volley right at us. There was a flare and then a CME, so several billion tons of plasma are headed toward us at a million miles per hour. Don't be scared, though! Our atmosphere protects us. Furthermore, we get a cool auroral display when this happens, so if you live in northern regions (or southern like Africa, Australia, etc.) you may get an aurora soon. Some satellites may have issues, but the astronauts on the Shuttle and space station should be OK.
SpaceWeather.com has details. They also have this cool animated GIF showing the fast particles from the event slamming into the SOHO satellite and leaving a zillion little spots on the detector. I have info about the SOHO satellite and how this all works on my Planet X page.
Also, this spot is being discussed on the Bad Astronomy Universe Today bulletin board, with some nifty pictures being posted too.