I’ve gotten a couple of questions about a quick little Windows Messenger Add-In I wrote after watching the Channel 9 Video about how IM works. You can get the information on how to write your own add-in for Windows Messenger at Katie Blanch’s Blog:
I like the design in that it can do some fun stuff, but not so powerful that I will have bots start talking to me. Security seems to be pretty solid and when an add-in is talking to you (instead of the person) Messenger makes sure you know it. I was able to write a quick add-in in about 10 minutes that sent a message to people that contacted me while I was in a full screen app (VPC or WoW) that I will be back in a minute.
Take a look if you have time.