The World Wide Web Consortium (W3C) has officially endorsed HTML 4.0 as a new Internet standard, giving its blessing to the latest version of the markup language that is used to create Web content. The W3C has been working on the HTML 4.0 specification for almost two years, in keeping with its oddly glacial pace. HTML 4.0 adds support for advanced form features, in-line frames, enhanced tables, as well as support for objects, scripts, and style sheets, according to the W3C. According to Netscape and Microsoft, these features have been available in browsers for some time.
The W3C is also offering a new service called Validator that will "validate" that Web sites conform to the HTML 4.0 specification. If you're into Web development, it's worth a look