When you call the splice method of ObervableArray on an array that contains objects that have a field of "isNew" the following error is thrown:
Property 'isNew' of object [object Object] is not a function
Here is a jsFiddle demonstrating the behavior:
http://jsfiddle.net/nbove/HgVEK/
Property 'isNew' of object [object Object] is not a function
Here is a jsFiddle demonstrating the behavior:
http://jsfiddle.net/nbove/HgVEK/