WordPress MU

How can an user be automatically registered with the role of "author" to several blogs when signing up for the first time?

For example there are 4 blogs.

a.blog.com
b.blog.com
c.blog.com
d.blog.com

When user "Rick" registers, I want him to be able to write posts for only :

b.blog.com
c.blog.com
d.blog.com

and NOT :

a.blog.com

How do I do that automatically upon sign up for every user?

You need to run the following code.

<?php
add_action('wpmu_activate_user', 'add_new_user_to_blog', 10);

function add_new_user_to_blog($user_id) {
// repeat this line with the blog id of each blog you want them added to in place of 1 - you could do it with a foreach loop
add_user_to_blog( '1', $user_id, 'author' );
}
?>

In which file do I insert the code above?

Before and after which line?

And does the code automatically give newly registered user 'author' roles to the selected blogs?

You'd save that code to a .php file and put it in the mu-plugins folder. It'll run whenever a new user is activated. And, yes, it makes the user an author on blogid 1, in that case.

I'll have a plugin out for this as soon as the new repo gets set up.

Thanks Deanna. Will be looking forward to try out your plugin.

Needs a better name...but here it is. I'm tired of trying to think of a better name....

http://wordpress.org/extend/plugins/wpmu-default-user-role/