"The bicycle industry is entering a new age of bike design. Changing culture and rising costs of resources are getting more people onto bikes, many of which are used for commuting, hauling groceries, or good old off-road fun. Xtracycle has been building the Free Radical kit for about 10 years, with other manufacturers such as Surly jumping on the bandwagon to create one-piece frames. Smaller fabricators are making their own bikes, and the demand for an open-source standard is increasing.
Xtracycle has therefore decided to put the basics of their Longtail design up for anyone to use. While we want to ensure the compatability of parts, we’re not charging money for the right to use our technology. We only ask that makers conform to a certain set of criteria, so that customers can be assured that everything will work well together." (http://www.xtracycle.com/longtailtech/index.php/Main_Page)