I am trying to acess a wcf service from a jQuery client
Specifically this example http://www.codeproject.com/KB/aspnet/WCF_JQUERY_ASMX.aspx#4
All works well
You might want to check out JSONP (JSON with Padding). In short, it involves adding a script element to the page with the web service url as the src. The web service then wraps the JSON as the first argument in a callback function, which is executed when the script is parsed.
Script elements are exempt from the Same Origin Policy, which is how they are able to get around this issue..