Google Releases Adwords API
Google has released an API interface for their Adwords program, using Soap 1.1. It looks like it provides access to all the features of the existing user interface, but no api access to the keyword sandbox.
They implemented transaction quotas based on dollars spent by Adwords accounts registered under your developer id. If you use up your monthly quota on the first day, your out of luck until next month. But they were nice enough to provide the getOperationCount and getOperationsQuotaThisMonth api operations to make it easy to keep track of.
Check out the Adwords Api Blog, the Developer Guide.