I use MariaDB on my Mac for most things that require MySQL. It's a drop in replacement for most things. Is there a special edge case with media wiki they had to solve or is it now just formally announced as being supported?
So, it's pretty much a drop-in replacement. But as with everything, time m ust be spent testing and so on before rolling it out to production. I believe a transition to MariaDB has been planned for a while now.
I remember I had problems with insert statements when previously with mysql inserts without default values worked but MariaDB was strict in this case and these inserts failed...
MediaWiki, the open source software that Wikipedia uses, now officially supports MariaDB.