On the Microsoft SharePoint Products and Technologies Team Blog, Troy Starr is writing a series of blog posts about alternate access mappings (AAM). AAM is something particularly tricky in a SharePoint deployment that you need to get right. Depending on the complexity of your configuration (intranet, extranet, SSL, ...) you need to configure AAM appropriately.

Check out part 1 and part 2. Part 3 is coming later.