The new Google Sites does include the feature to mark text as code, but all it basically does is changing the font and the background of the text. For example, with the feature from Google, the code would look something like:
<!DOCTYPE html>
<html>
<body>
<h1>My First Heading</h1>
<p>My first paragraph.</p>
</body>
</html>
Boring, right? However, there is help in sight! The neat website tohtml.com can translate any raw syntax into styled html code, ready to be embed in your site. Our toy example can thus be transformed to a more vibrant looking snippet:
A treat for my eyes and anyone reading through code!