The freedom to fork is the essential right of open-source software. Until Oracle's attempted acquisition of Sun/MySQL, however, few realized just how important it would be to retain the right to fork one's own code.
After all, just because you have the letter-of-the-law right to fork doesn't mean you have a meaningful ability to do so. So long as you're not the primary copyright holder, you're always going to be second place, with second-place commercial opportunities in the software.
MySQL co-founder Monty Widenius hints at this in his letter to the European Commission, citing conflicts of interest between Oracle and MySQL development interests. Such conflicts wouldn't be of such importance were it not for the lack of external commercial appeal that stems from MySQL's use of the GNU General Public License (GPL).
Even Richard Stallman, co-author of the GPL and founder of the free-software movement, and not someone that spends much time worrying about monetization of open-source software, gets this.
As noted in a letter co-drafted with Open Rights Group and Knowledge Ecology International, Stallman notes that Oracle's proposed acquisition of MySQL could hurt its development because the GPL reduces incentives to commercialize the code:
The acquisition of MySQL by Oracle will be a major setback to the development of a FLOSS database platform, potentially alienating and dispersing MySQL's core community of developers. It could take several years before another database platform could rival the progress and opportunities now available to MySQL, because it will take time before any of them attract and cultivate a large enough team of developers and achieve a similar customer base.
Given that forking of the MySQL code base will be particularly dependent on FLOSS community contributions - more so than on in-company development - the lack of a more flexible license for MySQL will present considerable barriers to a new forked development path for MySQL. [Emphasis added.]
For those who have been reading/hearing Stallman for the past 10-plus years as I have, this admission is shocking in the extreme. The GPL, which is supposed to be the ultimate guarantor of software freedom, may deliver the opposite. Because of its control-freak urges, it can stymie competition, which is presumably why Stallman is now calling on the European Commission to grant what his license couldn't: freedom.
Now consider if MySQL were licensed under the Apache 2.0 license. MySQL 2 could arise, take the code, hire all of the developers, and development of the open-source database would not miss a beat.
Could MySQL 2 achieve the same with the GPL? No, it could not, because the copyright holder, Oracle, would always have a superior commercial opportunity, because it has more rights than downstream users, as the GPL leaves the copyright holder with a greater range of business model options, and not simply support/services.
Apache leaves everyone--developers, users, vendors, etc.--on equal footing. The GPL does not. With the GPL, the copyright holder retains effective control.
That's one reason it has been so popular with commercial open-source companies, but the Oracle/MySQL situation may prompt more companies to consider using an Apache license so as to preserve maximum freedom in case of takeover, hostile or otherwise.
Disclosure: My company uses the GPL but has been actively considering areas to use Apache licensing.