WordPress MU

What's the "right" way to switch to another site in php? I want to update_option of a different site than the one I'm on (than the one that $current_site points to) and the only way I've found to do it is to modify $wpdb to "point" to the target site's option's table.

$wpdb->option = "wp_12_options";

Is there a "better" way to update the options of a site that's not the current one?

actually, my question is more around the activation of buddypress and how to do it for a different site than the one you're one, will create a new topic ..

the best way to update the options of a different blog is to switch to it using:
switch_to_blog( $blog_id );
then update_option
then restore_current_blog();