JQuery 1.6.1 Released - More changes to attr() for some booleans
blog.jquery.com
blog.jquery.com
Without any kind of type-safety or compilation in JavaScript, it's even more important for jQuery to preserve compatibility than libraries in other languages. You probably wouldn't discover some obscure breakages until the software using it is in production.
element.prop('property', value);
instead of element.property = value;