<p>I've created a custom list &amp; also added a column in the Announcement List.  Question is, how can I include those newly created items when I create a fresh Web Application (like a script, feature or something)?</p>

<p><em>Additional Info</em>: It's like when you're to deploy from your development machine to a staging or production server.  I'd like to have a script or something to update my production server to have the new column i've added to the Announcement List.  Just like SQL Server's ALTER TABLE command to update a SQL Server Table. </p>

<p>Is there an equivalent in Sharepoint Lists?</p>

<p>TIA!</p>

Your question is not very clear but I think you may want to look at Application Templates.
Microsoft provide 40 pre-built templates in the link below and the same technology is available to you. Links from this page should lead you to information showing you how you can crate your own.
Application Templates for Windows SharePoint Services 3.0
http://technet.microsoft.com/en-us/windowsserver/sharepoint/bb407286.aspx