I started a new project, microXMPP. It's a lightweight implementation of Jabber/XMPP protocol, written in ANSI C. The idea is to make XMPP protocol support applications, not applications support the protocol. Because of this, microXMPP is made as easy to use as possible, and as compatible as it could be. The code can be compiled under both Windows and Linux, and callback-based architecture avoids complex programming. Great for making XMPP bots and other Jabber client stuff!
The microXMPP project web page is http://xmppmicro.110mb.com/. All the sources can be downloaded from that page, along with documentation. In order to make things easier, a minimalist Jabber client is provided as application example. Small updates appear almost every week.