I don't normally waste an entry just pointing to another blog, but I thought I'd point out two cool entries by Ben Forta:
Building an IM Bot - Part 1
Building an IM Bot - Part 2
I read this articles and had a bot up and running in less than five minutes. The only problem is that there is one typo in part 2 of his article. Change this line:
<cfset var originatorID=CFEvent.data.originatorID>
<cfset var originatorID=CFEvent.originatorID>
I've registered "CFLibbot" and will be hooking up UDF lookup to it. I'm also considering hooking up RSSWatcher.com to it - so you can get notifications via IM instead of email.