Bug 134740 [Wizards] PDE product wizard is not obvious to use.
see attached image. The wizard for creating a new product opens with a file name initialized to ".product" which is selected. Generally this would imply that this is a good default but if you start typing you will replace the text with something else that is also a good name. If you require an extension for a file you should add it yourself like the "Export Archive" wizard.
bundles/org.eclipse.ui.ide/extensions/org/eclipse/ui/dialogs/WizardNewFileCreationPage.java
* responsibility of <code>createFile</code>.
	 * 
	 * @param filePath
	 *            the path of the file resource to create a handle for
	 * @return the new file resource handle
	 * @see #createFile
	 */
	protected IFile createFileHandle(IPath filePath) {
		return IDEWorkbenchPlugin.getPluginWorkspace().getRoot().getFile(
				filePath);
	}
	/**
	 * Creates the link target path if a link target has been specified.
	 */
	protected void createLinkTarget() {
		linkTargetPath = linkedResourceGroup.getLinkTargetURI();
	}
	/**
	 * Creates a new file resource in the selected container and with the
	 * selected name. Creates any missing resource containers along the path;
	 * does nothing if the container resources already exist.
	 * <p>
	 * In normal usage, this method is invoked after the user has pressed Finish
	 * on the wizard; the enablement of the Finish button implies that all
	 * controls on on this page currently contain valid values.
	 * </p>
	 * <p>
	 * Note that this page caches the new file once it has been successfully
	 * created; subsequent invocations of this method will answer the same file
	 * resource without attempting to create it again.