There are specialized search engines like sig.ma using semantic technology (but working in niches), and there are the big search machines slowly starting to use such an approach. Yahoo does it for some time already and Google goes RDFa and microformats.
Google looks for markup formats (microformats and RDFa) and displays reviews and ratings and also information about persons in Rich Snippets. New types of data beyond reviews and people will follow.
Googles Webmaster Blog describes this:
‘Imagine that you have a review of a restaurant on your page. In your HTML, you show the name of the restaurant, the address and phone number, the number of users who have provided reviews, and the average rating. People can read and understand this information, but to a computer it is nothing but strings of unstructured text. With microformats or RDFa, you can label each piece of text to make it clear that it represents a certain type of data: for example, a restaurant name, an address, or a rating. This is done by providing additional HTML tags that computers understand. These don’t affect the appearance of your pages, but Google and any other services that look at the HTML can use the tags to better understand your information, and display it in useful ways—for example, in search results.’