After creating your Google Doc (word doc, spreadsheet, or presentation), make sure you give is an appropriate name and give Google a few seconds to save the document. To publish your doc, simply go to the File menu within Google Docs and select "Publish as HTML".
Publishing the document to the Web essentially just makes it viewable as a webpage while it remains in your Google Docs directory of files. Publishing will give you both a document link that you can share with others or an embed code that can be added to a standard website page and viewed within that page.
Make sure that you check "Automatically republish.." so that you can continue to make changes to the original document and those changes will automatically be seen when viewing the original shared link.
Publishing the document as HTML is great for when you are sharing a document with someone who doesn't have a Google Docs account. The document is strictly a viewed webpage and any web browser can view it without having the user login to any account. Teachers can use published documents as parent newsletters, instruction pages for students, an easy 'home page' for a classroom, and a great way to share a report with the world.
How would you use this in your classroom? Do you have an alternate way of easily publishing a document so that it is seen by anyone with basic web access? Share!