There are several Drupal packages that allow various levels of integration with Facebook. I know that many developers like myself have been looking for a reliable package to integrate Facebook with their Drupal sites. For a while there were orphan projects and little development, but in the past couple of months there has been progress on multiple fronts. Last week's introduction of Facebook's social plugins and the revamping of their API will likely make Facebook connectivity ubiquitous across the web, making these modules crucial for Drupal. Here is a list of current projects and their statuses:
Drupal For Facebook: http://drupal.org/project/fb
This is the most complex of the packages, and it allows you to use Drupal to create a fully featured Facebook application. It is well-maintained by Dave Cohen who has recently completed version 2.0-RC1. On his blog, he indicates that he plans to soon start work on v3.0 using the newly revamped API: http://www.drupalforfacebook.org/node/1976 .
Facebook Connect: http://drupal.org/project/fbconnect
This project had been dead for a while, but the Drupal community revived it. It has active maintainers and seems to be in the late Beta stage (beta9). There may also soon be support for the new Facebook Graph API: http://drupal.org/node/778992#comment-2893374 .
FConnect by Vishal Sood: http://www.vishalsood.com/projects/drupal/facebook
This is a Facebook Connect made by developer Vishal Sood. It does not have a Drupal project page, but is available on his website. I believe he started work on it during the time that "official" fbconnect project was dead. The project is in beta, though I'm not sure if he is still actively developing it.
Facebook Share: http://drupal.org/project/facebookshare
Allows users to share a Drupal node on Facebook. Similar to the new "Universal Like" widget from Facebook.
Facebook Live Stream module: http://drupal.org/project/facebook_stream
This project allows users to see their Facebook "stream" of friends' updates in a Drupal block. It does not appear to be in active development.
Activitystream for Facebook: http://drupal.org/project/activitystream_facebook
This is similar to the Live Stream module, but is an add-on for the Activity Stream module: http://drupal.org/project/activitystream
Facebook Authorization : http://drupal.org/project/facebook_auth
This module allows people to login to a Drupal site using Facebook credentials. It does not appear to be in active development.
Facebook social plugins integration: http://drupal.org/project/fb_social
This is a new project that focuses specifically on integrating the facebook social plugins with Drupal (see: http://developers.facebook.com/plugins).
Facebook recommend by Durrok: http://drupal.org/node/779498
A module that integrates Facebook's new Like button. It does not have a project page yet. There is some discussion of overlapping features on the CVS application thread.
Facebook API: http://drupal.org/project/facebook_api
Appears abandoned.
Facebook Apps: http://drupal.org/project/facebook_app
Appears abandoned.
Gigya Socialize: http://drupal.org/project/gigya
"Gigya Socialize provides a single API that aggregates authentication and social APIs from Facebook Connect, MySpace ID, Twitter, and OpenID webmail providers including Google, Yahoo, and AOL."
Meebo: http://drupal.org/project/meebo
The Meebo bar allows users to easily share any content on your site to Facebook & Twitter via the Meebo bar that is placed at the bottom of pages.