From the discussion in the Seek The Peak trail thread I learned about the massive avalanche that occurred in the Ammonoosuc Ravine in late February 2010.
First blog post with photos here: Blog Post
Search his later posts for more photos as the debris continues to melt out.
Thanks to Brad's web cam image archive I was able to track down some before and after images of the slide path from across the valley. If somebody can narrow down the date using Brad's archive please post it here.
Please feel free to post more photos / information about the slide here.