The first thing that seemed weird was that all of a sudden the blog had 20+ new items.
That never happens. GWC is a blog that normally posts a 1-2 times per week, not much more than that. After clicking on the feed, I was presented with a large photo of some woman. I thought is this a joke? Anyway, I kept navigating through the posts and they were all large, well taken photos.
Here is an example: (Notice that I am in the GWC Blog and the url is poinging to the atom feed for GWC.)
Clicking on the feed details, you can see that something is amiss:
As you can see, something went terribly wrong here. It turns out that the feed seems come from a photgrapher named Joe Hewes. Looking at his blog, you can see that he uses Blogger as his platform.
My guess is that this was not a hack but a bug/error in Blogger. The actual GWC blog website has only its original (non photog) content. If it were a hack, GWC would likely have had its content changed as well.