Using A Web Service For Cross Site Scripting?

I want to pull down a feed (like twitter) and place in on a page using javascript (jquery). Ultimately, the "service" just needs to hand off JSON. I created a web service that allows me to do that, sort of. I don't know if using a stream reader is all that efficient and I was a little bothered by having to use what amounts to 2 evals on the clientside.

My question is twofold: is there a better method than using a web service and two, is there a problem with my implementation?

asmx:

[WebMethod]
public string World()
{
WebRequest request = WebRequest.Create("http://twitter.com/statuses/user_timeline/username.json?count=1");
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
StreamReader reader = new StreamReader(response.GetResponseStream());
string tmp = reader.ReadToEnd();
response.Close();
reader.Close();
return tmp;
}

aspx

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.4/jquery.min.js" type="text/javascript"></script>
<script>
$(document).ready(function() {
$.ajax({
url: "WebService1.asmx/twitter",
type: "POST",
data: "{}",
contentType: "application/json; charset=utf-8",
dataType: "json",
success: function(obj) {
var t = eval(obj.d)[0].text;
$('div').html(t);
}
})
});
</script>