MSN messenger
You can install MSN messenger as a plugin at least to Maemo OS2008 and Fremantle. This means that you can use devices integrated messaging software to chat with your friends at MSN.
Questions and answers
Will you be able to view messages that you have received while offline like you can on PC?
Is there a chat history?
Can you leave MSN running in the background and receive instant messages from multiple people while doing other things on the phone?
If i am for example watching a movie, will a message pop up saying i have an instant message from a contact?