As already mentioned two days ago every good website should have an option to search the content of the site. Although MCMS does not ship it's own search engine you can easily integrated 3rd party search engines with MCMS. Especially to integrate with the Search engine from SharePoint Portal Server Microsoft ships controls with Connector for SharePoint Technologies.
But honestly: I have never heard from a customer that he is satisfied with these controls as they do not allow any customization. Neither the look-and-feel nor the information being returned can be customized.
For prototyping these controls are ok but not to use them on most production sites. So you would need to implement your own search controls.