These are my notes on the Web Services as a Strategy for Startups: Opening Up and Letting Go by Stewart Butterfield and Cal Henderson.
This was one of the 15 minute keynotes (aka high order bits). The talk was about Flickr and its API. I came towards the end so I missed the meat of the talk but it seemed the focus of it was showing the interesting applications people have built using the Flickr API. The speakers pointed out that having an API meant that cool features were being added to the site by third parties thus increasing the value and popularity of the site.
There were some interesting statistics such as the fact that their normal traffic over the API is 2.93 calls per second but can beup to 50-100 calls per second at its peak. They also estimate that about 5% of the website traffic are calls to the Flickr API.