You can make a simple SOAP web services call to iControl from stand-alone clients. You aren't currently able to do so from within a web page containing AJAX because there are restrictions on connections made by the XMLHTTPRequest object based on the domain from which it was served. Because you can't necessarily serve the HTML containing the AJAX from the BIG-IP, attempts to connect to to BIG-IP via AJAX appear to be a cross-domain request, which is a security risk and not allowed by the browser.