D7 Core, includes Blog Functionality which may be worth a look.
Forums
and Facebook are different ways of addressing the same need. We provide both the
unmodified Drupal forums out of the box, and have a Facebook account. But you
need to look at your user population. The younger set will be on Facebook but
stuff disappears off the screen too fast to suit some uses. Of course email
lists are also part of this mix and more populated with the older set.
Until these issues settle down one usually has to touch all the
bases.
--
[ Drupal support list | http://lists.drupal.org/
]