The NOAA have started experimenting with an alerts page offering both RSS and XML feeds. The XML feed is CAP, or Common Alerting Protocol. There is a mini-FAQ explaining CAP. It is briefly described on the NOAA page:
Common Alertings Protocol (CAP) is an non-proprietary standard data format for the interchange of hazard warning and reports.
This is an experimental service, and any comments should be submitted to the feedback page by December 30, 2003. Submitted comments will "help determine the future of the product".
News of this was posted to the RSS Weather mailing list. You can view (and respond) using the web forum, as well as subscribe to the list.