wordpress 3.0 json issue

When I comment out the line:

@header('Content-type: application/json; charset=UTF-8');

it works for me

p.s.

1. there is also a closing php opening tag in it without the word php
2. there is a closing php tag at the bottom which can be gone
3. there is a notice on an undefined index.
4. better would be to use $charset = get_option(‘blog_charset’);

I have no idea if this: http://wordpress.org/support/topic/plugin-json-api-content-length-header has something do with it, or this: http://core.trac.wordpress.org/ticket/11537 or this: http://wordpress.org/support/topic/wordpress-gone-wild?replies=3 , did not dive in it.