XWiki just got upgraded and now has some default macros of Instant Messenging Presence indicators for Jabber, Skype, AIM, Yahoo and MSN.

You just need to put:

Code	Example ID	Comments	Result
	ldubost@jabber.org	Add edgar@jabber.netflint.net to your list of users
	ldubost	register on http://www.jyve.com and add Jyve01 to your list of users
	nvludo	make sure you accepted anybody to contact you in the security preferences
	ludovic	make sure you accepted anybody to contact you in the yahoo profile
	ldubost@hotmail.com

Please note that not all these presence Indicators are run by the respective Instant Messenging networks. They (and of course myself) cannot give guarantees that it works all the time. At the time of posting this note, the Skype presence for my account is incorrect since I'm online like on the other networks.