We know our users like to be able to customize their websites and wikis to their own style, and with our recent release we have added more flexibility and control over the layout of Google Sites. Now you can change the width of your sidebar and header (previously the height of the header was defined by the logo) or turn off the sidebar and header entirely. You now have control over the width of your site, which previously was always 100% of the browser width. You can also set the width of text boxes if you do not want your content to fill the whole space of the page by default.
Also in the latest release is tighter integration with Google Docs and Webmaster Tools. When you want to embed one of your Google Docs documents, spreadsheets or presentations, you can now conveniently select it from a list rather than pasting the URL into the document. With Google Webmaster tools, it is easier to see how Google indexes your content and if you enable the integration, you can also auto-generate a sitemap to submit to Google. (Learn more.)
There are several other small improvements in Google Sites that you may notice. Site editors can preview their site as it would look to a regular viewer. To do so just select, "More actions -> Preview as viewer." In addition, if you don't want viewers to have visibility into site activity, simply remove the element from the sidebar and the link will also be removed from the footer.
Posted by Adam Howell, Software engineer
Google Sites Blog: More layout control and better integration with Google Docs and Webmaster Tools