Currently, at least these public projects use gloox:

• joline: a jabber component which allows for sending offline messages to MSN users
• Kinapsis: a multi-protocol IM client for KDE
• Scribis: a native chat client for SkyOS
• XFireGateway: a gateway that bridges Jabber with the XFire network
• fconmgr: a FastCGI implementation of HTTP Binding for XMPP (XEP-0124)
• JabberMonitor: a monitor for the xmpp network
• FatRat: a Qt4-based download manager for Linux
• CJWPres: C++ Jabber Web Presence

Amongst others, gloox is also used by: