Great news for all the Google-Addicts: the GData group has just added JSON interfaces for their services! From the official post:

For those of you who have been trying to build client-side GData mashups but have been thwarted by the same-origin policy, we have some good news for you: you can now get public Base, Blogger, and Calendar feeds as JSON! This means that you can start displaying GData in your web page with a little JavaScript.

In other words it is now possible to define a callback function and simply add a script-tag to your page, and the browser will go and fetch the data, that will then be handled by that function. No need for the server to proxy the data through, eliminating the need of complex caching mechanisms, just fetch the data from the source

 function handleJson(json) {   alert("The title of the feed is: " + json.feed.title.$t); }

It’s as simple as it gets. Being the browser the one who fetches the data greatly improves speed and reduces bandwidth for the originating server. Supported Services for now are:

• Google Calendar
• Google Base
• Google Blogger

but I’m sure more will follow soon Just take a look at the official post for more information.