Reports started coming in a couple of hours ago (here) of a firing incident across the Limit Line, hitting Yeonpyeong Island. (Link note: Google Maps does not show the Western Sea Border. The island is South Korea; The nearby mainland is North Korea.)
Don't bother going to Reuters, The AP, or other such wire services yet. They are all citing YONHAP... which I conveniently have the direct link to their story. Check the mainpage there as well, for they have both a photo news section with good pics on this *and* you can bet there will be followup reports and related political news.
First Glance Analysis: This is another provocation incident. Not a very clever one either. The primary target may have been ROK elements involved in the "Hoguk Exercise", but the damage seems fairly widespread and as the report says, the shelling fell well south of the exercise area. The pressure on the Lee administration to do something is going to be fairly intense, but like after the Cheonan sinking, picking *what* to do and *when* will be very important.