$i = 0; //number in array before loop starts
$allposts = array();
$postslist = get_posts(‘numberposts=10&category=1′);
foreach ($postslist as $post){
setup_postdata($post);
$allposts[$i] = $post->ID; //get post id for each post
$i++;
// code to apply to each post goes here. use $allposts[$i] as the post (basically accounts for all of them) you want to edit.
}

ID; // Get post ID for each post in category.
$i++; // $i increments to go through array each cycle through the loop.
//Here’s where you want to include the code that adds the tag to each post. (each time through the loop, it’s working with a new post)
}
?>
This function, you can just take out ‘numberposts=10′ to go through all posts in category (I haven’t double checked that, but it should work)
$postslist = get_posts(‘numberposts=10& category=1′);

Here’s all the functions used for further options:
array() –> just look up php array for more details
get_posts() –> http://codex.wordpress.org/Template_Tags/get_posts
*You need the category ID here. To make things a lot simpler, you can install this plugin to show ID’s of posts and categories on admin pages for WP 3.0: http://wordpress.org/extend/plugins/simply-show-ids/

foreach ($postslist as $post) {} – make sure you have those open/close squiggly brackets around function.
- http://php.net/manual/en/control-structures.foreach.php

Of course adjust the opening and closing php tags according to context.

I could go into further detail, but given you made this comment 2month ago, you’ll probably never see this. Anyone who would like more help, feel free to e-mail me at: david@origamifolder.com

cheers!

Here’s the full documentation:
http://codex.wordpress.org/Function_Reference/wp_set_object_terms

Any chance you could include the link at the bottom of your post for those who’d like to understand it more completely? Thanks!

Cheers!

I’ll see what other fields are supported and update this.

One suggestion – don’t hardcode it for “circulation” field, make it more flexible (like Twitter snippet that can fetch bunch of different stuff). There are some more fields that can be fetched (“reach” and something else I don’t remember) .

Kind regards,

Christian