Can we use Chat messenger (the chat widget) in a Visualforce page? I have force.com Sites (as portals), and I want to include a chat messenger in it? If this isn't possible, any other ideas on how to implement messenger features?
I believe so.
This page from Salesforce states that you can enable or disable within the visualforce https://developer.salesforce.com/releases/release/Spring12/chatter+messenger
Quote from the page: "Developers can disable Chatter Messenger functionality within specific Visualforce pages by setting “showHeader” in the page component to false, or by changing ContentType to something other than text/plain."