Petermann Glacier in northern Greenland has calved a massive iceberg. Cracks in the glacier's floating tongue prompted scientists to install monitors last summer to watch for sections beginning to separate.
Today the sun emerged after a few days of cloudiness that had shrouded the glacier from satellite view, revealing a dramatic break-up.
As best I can estimate the iceberg is about 18 miles long. Another large crack further up the glacier appears to have widened. The floating ice at the top of the image is sea ice that's exiting the arctic ocean, not icebergs from the glacier.
For detailed daily images of the entire arctic, you can explore the MODIS Arctic Mosaic. Click on any section of the mosaic to see the individual tile, and you can view much larger versions of every image as well.
I have yet to see any news stories or blog posts about the breakage, but I will update with news as it appears.
Update:
Shpilk has found more discussion and a video animation. Their size estimate is that the main ice island is 250 square kilometers, with 30 or so more square kilometers of smaller breakoffs.