The official update from Apple registers as build 4L13, and is highly recommended for all OS X users. According to Wincent.org:
Apple has made Mac OS X 10.0.1 available through the Software Updates pane (in System Preferences). If you have already installed 4L5 or 4L7 youill find that the SU pane canit see the new update (4L13). To remedy this, you will need to use the terminal.
You can find the full instructions at the Wincent.org Web site.