I'd go with gogodr's solution, it'll be the simplest for you - BUT ONLY IF you just request public ticker data, you should in NO CASE send private user-data (passwords ect...) through 3rd-party proxy-services.
If you want to read more about JSONP and how to evade the cross-domain issue for JSON-requests, you can take a look here:
http://en.wikipedia.org/wiki/JSONP (or google for JSONP)
Thanks to gogodr, that should work just fine, and of course I'll only be using it for non-private information.
The only other thing to be careful of is that you're now putting yourself in the hands of whateverorigin: they could send back false or even malicious data. Not that I have any reason to suspect that they would, but it's just something to think about.
If you whant to make a site that would display API data from multiple exchanges and display it to the user use php better!
He could still be using PHP; he just wants the client to load the information instead of doing it on the server.
if that ever were to happen, they have their whole project open sourced. Anyone can take the source and make his own whateverorigin.
There are a couple of limitations though. you cant POST or GET parameters using whateverorigin.