H MS Messenger
Microsoft seem to think that all smartphones etc with windows CE 5 will have MSN Messenger built in. A bit more digging and it seems some do & some don't. OURS DON'T!
Someone just let me know where it is so I've uploaded it here!!!
Windows Live Messenger which
should have been included with windows mobile version 6.
It clashes with the BT software so that could explain why it doesn't come
installed as standard
Pocket Messenger is apparently available (I've not tried it) at an extra charge (that's why I've not tried it) from Handango
You can also messenger via the web starting at http://mim.live.com