I think the Digg API is a huge step forward for Digg, and it is about time that they got one. But it has been possible to build apps on top of Digg already before, check out Personal Digg RSS built on openkapow.com way before the Digg got it's API.
Great article about a very interesting subject. I think you would also find openkapow.com interesting if you are into web scraping. Openkapow allows you full control over process flows etc when you do the scraping, and it allows you to solve much more complex use cases than any other tools on the market.