I've been running into a problem querying GData (Google's Data APIs) using jQuery and JSON. jQuery's ajax function automatically adds a cache-buster timestamp to the query, and Google is barfing on it.
The timestamp is inserted starting around line 2608 in jQuery 1.2.3. As an example, here is an example JSON query url as sent by jQuery: http://gdata.youtube.com/feeds/videos/ysTmUTQ5wZE?alt=json-in-script&callback=jsonp1204907988594&_=1204907988789 That returns "Invalid query parameters:_" Removing the underscore timestamp parameter and Google returns the JSON object: http://gdata.youtube.com/feeds/videos/ysTmUTQ5wZE?alt=json-in-script&callback=jsonp1204907988594 In the end, I ended up inserting the JSON loading script tags into the page the old-fashioned way, missing out on all benefits of using jQuery for this. I'm also filing a bug with Google encouraging them to fail a touch more gracefully when faced with unknown query parameters. Please star issue 390 to help get their attention: http://code.google.com/p/gdata-issues/issues/detail?id=390