Responsive Design is an Official W3C Recommendation
The W3C (World Wide Web Consortium) is like the United Nations of
web development: a consortium of browser makers and interested parties
that generates recommendations and resolutions. Also like the United
Nations, the W3C's resolutions and recommendations have no legal power
and only take effect when browser makers (and designers and developers
in general) implement them of their own free will. The process of going
from idea to official recommendation is fraught with bureaucracy, and
the W3C has frequently been criticized for its glacial pace.
Surprisingly, however, the W3C is ahead of the curve when it comes to mobile web design. In July 2008, the W3C published its "Mobile Web Best Practices" as an official W3C Recommendation. The document describes many of the same concerns that responsive design and Mobile First advocates have been touting recently - the challenges of smaller screens, more limited input, and costly and limited bandwidth.
But the most interesting part of the document is section 3.1, "One Web". In this section, the W3C officially endorses the principles of responsive web design by stating that designers should work toward the principle of "One Web". According to the W3C, this means "making, as far as is reasonable, the same information and services available to users irrespective of the device they are using" - the same belief that underlies responsive web design!
Going even further, the W3C recommends that designers prepare for screen widths of 120 pixels and total page weight of no more than 20KB as a "default delivery context," not to mention "no support for client side scripting" - no JavaScript, at all. These are difficult targets to reach in practice, but they underscore the idea that content and context can be worth far more than an attractive but limited layout. Meeting these goals in a "mobile" representation of your site lays a solid groundwork on which to build with progressive enhancement through media queries.
The remainder of the document is a list of best practices with examples and explanations, but to call these simply "Mobile Web" best practices is a bit of a misnomer. These principles can (and in fact should) be applied to any website's design. There isn't a single site on the Web that couldn't benefit from looking at the balance of number of links on a page vs. number of clicks required to get to a page, or ensuring that information conveyed through color is also discernible without the use of color.
So, believe it or not, 2008 was a pivotal year for mobile web standards. If you're designing a website (or if you own a website), you owe it to yourself to read through the W3C's Mobile Web Best Practices. Even if you don't expect mobile users at your site, taking these suggestions to heart will result in a better experience for all of your users, in the spirit of One Web.