Do you use ICQ, MSN Messenger, Yahoo, AOL Messenger, all at the same time? What a list of presence-indicator and instant communication software!
Jabber is an open XML protocol for the real-time exchange of messages and presence between any two points on the Internet. It is a multi-platform communications standard that allows interoperability between these instant messenger products.
Antepo released a series of Jabber products for the handhelds: it includes Pocket PC, Smartphone and J2ME clients. There's a free trial version available for download in their pages.
The Jabber official page has downloads for all major platforms. For more information on Jabber click here, or follow the link below for Antepo's products.