How to create a sort of site-wide group chat with PHP, Javascript & CSS that will work with Wordpress

Just not sure where to start. I'd like something similar to the chat box on http://www.shadowness.com/ or group chat on Facebook or Gmail.

I can style the css myself, and the javascript no problem. I need some sort of beginning php script to build off of. Where could I find one, or how would I go about making a basic footer chat? It doesn't need any fancy features, just emoticons, and show who's online. I could probably make a chat page, but I have no idea how to get it to work with wordpress logged in users.

Thanks for the help. Would this be something I could realistically achieve in a week or so开发者_StackOverflow中文版?

I would take a look at Comet & PHP: How to use Comet with a PHP Chat System? but you should know that there are a number of things you must consider when making a chat system, most importantly the system you use. There are plenty of plugins out there for this that are based on a comet system - here is a good article on the concept: http://www.zeitoun.net/articles/comet_and_php/start

I would advise going with a plugin to do the heavy lifting, because in my experience you need a lot of time and a lot of effort to implement a chat system like the one you have described.