The GNU Public License first saw light at the hands of Richard Stallman, probably the single most important activist in the Free Software movement, and founding member of the Free Software Foundation. After its slow initial adoption, the current version 2 of the license has been in widespread use and the reason it's known now undoubtedly lies in the fact that Linus Torvalds chose to release his Linux kernel under it.

As in free speech, the free in free software has nothing to do with price. It refers to freedom; freedom to study, redistribute and change the software you use. This is the underlying philosophy of Free Software - it tends to form communities where people (and companies) help each other.
In today's world of proprietary software and patents awarded for pretty much anything, such free software needs the protection of a license - the GPL.

It's unsurprising that the most significant changes in GPL version 3 have to do with patent law, since many members of the free software movement have always taken strong opinions against software patents. In its current incarnation, in addition to the protection offered by the previous version, the draft also mentions penalties against infringers. As such, a company accused of infringing on free software patents would be unable to distribute its product.



Another predictable addition to the license is mention of copy - restriction technologies. Even disregarding the obvious incompatibilities of DRM and Stallman's views, use of GPL'ed software on devices with digital rights management restrictions may lead to questions of the validity of GPL licenses - something definitely undesirable due to the Digital Millennium Copyright Act and countries increasingly adopting similar laws: products adopting the new license would suddenly remain in the open if courts decided the GPL is invalid.

It still remains to be seen whether version 3 will achieve the same degree of success enjoyed by its precursor, since Linus doesn't seem to be interested in changing Linux' legal face.