XMPP sender allows to send (and receive) notifications about new comments in blog. Also it can override email function to xmpp for your blog.
Put XMPP-sender folder into [wordpress_dir]/wp-content/plugins/
Go into the WordPress admin interface and activate the plugin
Go into the WordPress admin interface to the XMPP options page and customize server options and messages template. You can test server options using button "Test" after saving options.