Apache Foundation has taken a stance against using React.js and other popular software using this license. This may be of relevance for projects like Gutenberg and Calypso that use React as I'm not sure that the license questions were ever addressed. The Apache Foundation asked Facebook if they would consider changing the license.
Post script to the Wix/GPL #drama from last year. Wix has now forked from the editor WordPress originally forked from, which has an MIT licence, so basically everything is now fine.
In late October 2016 Matt Mullenweg, the co-creator of the WordPress blogging platform attacked the company Wix for not complying with the GPL License. The rich text editor in their competitor, Wix, app was using GPL code - which was itself a fork of an MIT licensed code. The problem was that the Wix app was using a GPL licensed library released by the WordPress project, that would have essentially meant that the entire Wix mobile app's source code be released. This is what lead Mullenweg (rightfully) to announce:
This explicitly contravenes the GPL, which requires attribution and a corresponding GPL license on whatever you release publicly built on top of GPL code. The GPL is what has allowed WordPress to flourish, and that let us create this code. Your app’s editor is built with stolen code, so your whole app is now in violation of the license.
- Wix and the GPL
This then lead to a minor shit storm among the GPL and WordPress faithful against a commercial entity abusing Open Source code. As things usually go, this calmed down in a few days and people forgot about it. What went largely unnoticed was the fact that, while Wix was technically breaching the GPL license, the WordPress
This is sad indeed. Especially if you intend to use it on a Buddypress project.
Your license is also revoked if you have any legal disputes if you have legal disputes with any other company using React. This is the reason why both Google and Microsoft employees are not allowed to use React.js in their work - according to Rob Eisenberg, creator of the Aurelia framework and a former member of the Angular 2 development team.
While this may be a theoretical impact for most implementation projects, it's certainly worth remembering and can limit some other projects like WordPress Calypso which have built a deep coupling to the library. Automattic, the company behind WordPress, is no stranger to petty litigation,