You can do that using javascript on the browser.
Look for a JSON feed in the Yahoo API, that delivers JSON with a callback function, ie:
http://search.yahooapis.com/.../news?results=20&output=json&callback=myCallBackFunction
Then in your page have a global function:
function myCallBackFunction(json){
//show here the json feed as HTML
}
This technique is commonly called JSONP
You save some latency for your users by avoiding your PHP to proxy the requests.
And you won't pay the bandwidth for these data, as they come directly from Yahoo.
Unfortunately, all this is valid only if your target audience is javascript enabled.