convert can.Observe to plain object

in JMVC3.3/canJS attributes set by attr() are no longer simple objects, but can.Observe objects. Whenever I try to use these data in an ajax request buildParams fails.

example:

1. var params = can.Observe( {
2.       extent : {
3.             east: 5.9700203118605,
4.             north: 52.211401605631,
5.             south: 52.211118448568,
6.             north: 5.9684737677777
7.       }
8. });
9. 
   
10. $.ajax( {
11.       type: 'GET',
12.       url: 'http://bag.dotkadata.com/Bag/Extent',
13.       data: params,       
    
14.       dataType: 'json'
15.  }).done( function( result ) {
16.       console.log( result );
17. });

See it at work: http://jsfiddle.net/nvnYU/7/

So my question is: How can I get a plain object again from an observable?