Jacek Kopecký, Tomas Vitvar, Carine Bournez and Joel Farrell have published an overview paper on SAWSDL in the December issue of IEEE’s Internet Computing. It is unfortunate that IEEE does not put its proceedings into the public domain, but, well… Maybe some of the readers have access to IEEE’s Digital Library. In any case, here is the abstract of the paper:
Web services are important for creating distributed applications on the Web. In fact,they’re a key enabler for service-oriented architectures that focus on service reuse and interoperability. The World Wide Web Consortium (W3C) has recently finished work on two important standards for describing Web services: the Web Services Description Language (WSDL) 2.0 and Semantic Annotations for WSDL and XML Schema (SAWSDL). Here, the authors discuss the latter, which is the first standard for adding semantics to Web service descriptions.
 Kopecký, Jacek, Tomas Vitvar, Carine Bournez, and Joel Farrell. “SAWSDL: Semantic Annotations for WSDL and XML Schema.” IEEE Internet Computing 11, no. 6 (2007): 60-67. See also the online reference on the IEEE site.
Addendum on the 29th: Jan Zemanek commented that the paper is available on-line on Tomas Vitvar’s site! (Thanks Jan)