Updated May 10, 2010 Chatroll widgets are no longer working on wordpress.com blogs.
In January I was flabbergasted to read in a wordpress.com forum thread that there were chatboxes that are iframes embeds operating on some wordpress.com blogs. As there are some that have passed through “filters” and are trusted by wordpress.com I don’t know why the support documentation does not reflect this. Perhaps listing exceptions is problematic. In addition to the meebo chatbox widgets that we can use on wordpress.com blogs, and there are three other options I want to share with my readers.
To use chatback, you must have a Google Talk account … but your visitors don’t have to! They don’t even need to have an email address, or to have ever used instant messaging. See Howto: Google Talk badge on wordpress.com