Sometimes other folks can say it better than I can so I'll let Olivier tell you what's up with Google's new AdWords API and what it means.
"Some possibilities might include:
- Generating automatic keyword, ad text, URL, and custom reports
- Integrating AdWords data with databases, such as inventory systems
- Developing additional tools and applications to help you manage accounts"
Code samples are provided in Java, C#, XML, PHP and Perl, with more emphasis on the last one. There's a discussion group for developers and a blog, though they're obviously not very busy places yet. They use an interesting quota system to throttle API calls based on ad spending.