This was only a matter of time. You can talk about the sleek UI or the great Flickr tools that allow for this Media Center application. But what's most significant here is the power of an open versus a closed platform.
It can take at least 3-4 years for the most interesting applications to reach a cable or satellite settop box. Business development, testing, lab certification, customer support training and deployment are but a few of the hurdles between a new service and your TV. And forget about it if the application requires new hardware. STBs have 4-5 year half-lives.
The Internet has shown the power of open distribution and easily accessible tools. With the Media Center, one creative individual can now bring a rich, community-driven photo sharing universe to the TV. A friend of mine calls this concept "The Lindsay Channel," after his daughter. It was his dream to see this type of functionality come to millions of TVs. EB, I guess it's here.