This is the first in a series of posts in which we'll be posting short opinions of some of the available XMPP clients, in the run up to the launch of our XMPP server, M-Link.
There is a good choice of the Internet Standard XMPP (eXtensible Messaging and Presence Protocol) clients for all common desktop platforms, including decent quality free products.
We have not found a good free mobile XMPP client, but Agile Messenger from Agile Mobile is a neat commercial one. It's reasonably priced at 45USD and you can try a free seven day trial version prior to purchase. It runs Windows Mobile and on a wide range of Nokia and Sony Ericsson phones. It's very easy to set up and use, and does everything you would expect a mobile XMPP client to do. Importantly, it makes good use of the limited screen size on mobile phones with a tidy layout and adjustable font sizes.