To have a "following" function, you might consider using the Flag module:
<a href="http://drupal.org/project/flag" title="http://drupal.org/project/flag">http://drupal.org/project/flag</a>
It allows users of your site to "flag" other users (or nodes for that
matter).

Of course this doesn't subscribe them to the users they are following (even
though you could list followed users content with Views module)
For that functionality you might want to check out the FriendList module (
<a href="http://drupal.org/project/friendlist" title="http://drupal.org/project/friendlist">http://drupal.org/project/friendlist</a>) which integrates with a couple of
other modules to probably provide the functionality you are looking for.

2009/9/7 Aldo Martinez Selleras < ... at caonao dot cu>