GZRBOT is a port of GOZERBOT to the Google Application Engine. It is there for its code and reuse of it is highly recommended. A script is available to clone gzrbot and rename it so you can run your own bot off the GZRBOT code. GZRBOT has a plugin system that lets you program your own plugin and provide you a way to add custom functionality to your bot. Both writing commands and reacting on events through callbacks is supported.
jabberd is a Jabber/XMPP instant messaging server. It implements XMPP-Core (RFC3920), XMPP-IM (RFC3921), and a range of protocol extensions: XEP-0012, XEP-0016, XEP-0030, XEP-0049, XEP-0054, XEP-0077, XEP-0079, XEP-0092, XEP-0114, XEP-0138, XEP-0153, XEP-0157, XEP-0160, XEP-0191, XEP-0192, XEP-0193, XEP-0198, XEP-0199, XEP-0202, XEP-0203.