I have verified this with some of my other friends with HTC legend, and some with nexus1, and myself on VIllianROM and SuperHero ROM, so afaik its a property of vanilla contacts, .... if you have a contact with an msn/hotmail or yahoo email, there is, along with a email link in the contacts page, a 'chat' link. For example my buddy has @hotmail.com address and i saw a link named 'chat using windows live' right under 'email <name>'. why is that there? so far my searches have yielded that some tmo phones (g1?) came with a IM app preinstalled that used to be able to take the intent thrown out by clicking that (i verified using logcat, it does indeed throw out an intent that looks the same as when u click the 'talk using google talk' link except its msn:// and not gtalk:// .However so far i have not had any luck flash updating with that app, nor installng any other IM app, none actually look for the intent and act on it, logcat simply reports "unknown action for intent" or something similar.