Kopete is Instant Messenger specially design for Unix workstations (including Linux, FreeDSB, Windows, Solaris, Mac OS X). Sometime Kopete called as KDE Instant Messenger because of its designed for KDE. Kopete can be categories as multi protocol instant messenger that can be used for AIM, Windows Live Messenger (WLM), Yahoo Messenger (YM), Gadu-Gadu, ICQ, Novell GroupWise Messenger etc.
You can even used SILC or Anti Spam Plugin along with Kopete. This could be means that Kopete would be very secure for Instant Messaging (we knew that SILC is a secure way to make a chat or conference)