Here's how to try Google Drawings and the new interfaces of Google Documents and Google Spreadsheets:
* create a new drawing by opening the documents list, clicking on "Create new" and selecting "Drawing".
* to see the new document editor, go to the settings page, click on the "Editing" tab and select "Create new text documents using the latest version of the document editor." Unfortunately, you can't see the existing documents in the new interface. The new document editor is code-named "kix" and it's a completely new application.
* to switch to the new spreadsheets editor, open a spreadsheet and click on "New version" at the top of the page. All spreadsheets will now open in the new interface.
The new interface is not yet available for presentations.