WSO2 WSF/C is a standards compliant, enterprise grade, open source, C library for providing and consuming Web services in C. WSF/C has the most number of WS-* specs implemented such as WS-Addressing, WS-Security, WS-Reliable Messaging, WS-Eventing, WS-Policy and so on. Other than that it has many features such as XMPP transport implementation, Command line tool for consume web services (wsclient). You can find complete feature list here. If you are concerning about licensing WSO2 WSF/C is under Apache2.0 licensing.
With WSO2 WSF/C 1.2.0 Release , it gives more and more on WS-Security , there is improvements in other features as well, refer this for release note.
If anybody wish to send appreciations, blames, flowers, beer, food, T-shirts, money, etc please send them through wsf-c-dev@wso2.org , we already received some 
Don't believe me, look here.
