According to a recent article ("Lack of Skilled Devs Slows Web Services") in Integration Developer News, a lack of skilled developers is hampering the adoption of web services in the enterprise. Development managers are having a hard time finding people who understand the various specifications and the ways to build the interfaces.
Based on a study by Evans Data Corporation, the article indicates that developers are having trouble with technologies such as XML Schema and XML DTDs, and points out that writing these can require considerable experience.
In the same way that a good writer must usually spends a lot of time reading, we'd like to suggest that aspring web services developers use the various Amazon Web Services as learning tools. After you've built a real application using the E-Commerce Service, the Alexa Web Information Service or the Simple Queue Service, you have some legitimate web services experience. This experience may come in handy on the job, and it certainly won't hurt to add it to your resume. You can also study the DTDs and Schemas associated with these services to see some examples of how they are built.