post_content_via_json.php

<?php

/*
== Requirements == 
http://wordpress.org/plugins/json-api/ on the source domain.
*/


/*
== Usage == 
[json_include url ="http://domain.com/url"]Enter fallback content here.[/json_include]
*/

/* 
== Shortcode == 
Using page caching or caching the result in a transient for 24 hours 
is probably a good idea from a performance perspective. 
*/

add_shortcode( 'json_include', 'json_include_sc' );

function json_include_sc( $atts, $content ){
    
    extract( shortcode_atts( array(
		'url' => '',
	), $atts, 'json_include' ) );
    
    if( !$url ) return $content;;
    
    $url = add_query_arg( 'json','1', $url );
    
    $response = wp_remote_get( $url );

	if( !$response ) return $content;
    
    $post = json_decode( $response['body'] );
    
    //echo '<pre>'. print_r($post,1) . '</pre>';
    
	if( isset( $post->page->content ) ) {
		return $post->page->content;
	}else{
		return $content;
	}
    
}
    

Written for:
http://www.quora.com/WordPress/How-can-I-get-a-wordpress-page-content-from-another-wordpress-instance-on-a-separate-domain