Originally Posted by Old Pedant
Oh, and HTTP Long Polling requires a certain type of server. Unless you have your own dedicated server, you probably can't use it.
anything with PHP ought to be plenty, especially if it has APC installed. .NET works as well. I would recommend EventSource over ajax, but it's best to have a stack so you get high-efficiency pipes like WebSockets and backwards-compatibility via flash/ajax/jsonp so you can use a common high-level interface for all browsers.
BROWSER STATS [% share]
(2013/10/31) IE7:0.5, IE8:8.6, IE9:5.3, IE10:12.3, FF:17.7, CH:41.8, SF:8.1, MOBILE:20.4