For those new not in the know or new to Open Source, GPL is an acronym for General Public License. Today marks the release of version 3 of said license, hence GPLv3. The GPL is licensing similar to, but almost completely opposite from a standard Microsoft End User License Agreement.
Where Microsoft’s EULA’s are to prevent you from sharing or using their software other than specfically directed, the GPL generally protects you to allow you to copy, modify and distribute the software in any way you see fit, so long as you give proper credit where it is due, and you provide the original source code along with your modifications.
What’s new in v3? Lots, but not much really. The core is still the same as the first two, it adds a few more restrictions on corporate cross pollination (Microsoft/Novell) and tivo-ization in an attempt to further protect the contributions of free software developers and end users alike.
Here’s the biggest change, straight from the Preamble talking about these two very things:
“Some devices are designed to deny users access to install or run modified versions of the software inside them, although the manufacturer can do so. This is fundamentally incompatible with the aim of protecting users’ freedom to change the software. The systematic pattern of such abuse occurs in the area of products for individuals to use, which is precisely where it is most unacceptable. Therefore, we have designed this version of the GPL to prohibit the practice for those products. If such problems arise substantially in other domains, we stand ready to extend this provision to those domains in future versions of the GPL, as needed to protect the freedom of users.
Finally, every program is threatened constantly by software patents. States should not allow patents to restrict development and use of software on general-purpose computers, but in those that do, we wish to avoid the special danger that patents applied to a free program could make it effectively proprietary. To prevent this, the GPL assures that patents cannot be used to render the program non-free.”