Credit goes to ployer from this thread for the discovery.
You can see at the store they are indeed free.
Facebook/Twitter message from Unity:
Licenses must be activated before April 8th or they will not work.
Licenses do not expire once activated.
I will edit this post when more information becomes available.
Enjoy!
Yes, it is indeed free!
I have found the info on the same topic, and obtained them! This is fine day!
Thanks Unity!
Holy crap, and to think on Wednesday I was going to spend $800 on both of those, this is most excellent news 
I was actually hoping for a discount around GDC, but this is so much better
I’m guessing here that they’re pushing Unity for a more Freemium model. They give out the software for free, and recoup their costs via the asset store and up selling the Pro versions + Support.
Guess christmas came way early this year! - Thanks Dman for the notice, and Thanks Unity! This is unexpected and very very awesome
Edit: The key just came in the mail - it’s hard to express the exponential awesomeness that is the Unity team- If I ever get the chance, I will buy each and every one of you a beer! (and all your future software of course).
Unity! Despite getting an automated congrats, how did you know it was my birthday today? Huge amount of Kudos to Dman and Unity.
I’m having a hell of a time signing in to take advantage of this offer. If it continues I’ll send a report, but I’d imagine this is an issue of people overloading the server.
wow, store seems to be flooded with visitors… so it seems. 
Unity, add some extra horsepower to the store (extra machines e.g.), with such an offer you could have expected major attention in visitors numbers (means lots of traffic and computing power needed).
This is awesome if it is genuine offer (not hacked store e.g.)
I see no mention of this special offer anywhere else on the website though… odd, you would expect this (e.g. in the news, or blog section at least)
Wow!
The Unity Store doesn’t work for me,unfortunately.It says 500 Internal Error,i’ll try again in half an hour
Also,thanks Unity!Meanwhile:
thats great!, BUT sad for me i just bought unity ios basic few months ago 
… hahahaha the same happened to me with unity indie and then unity free.
its until april 8, says on facebook and twitter
Awesome opportunity 
Now I’m biting my fingers because I bought Android license some 3 weeks ago
Yeah it’s taking a beating right now, we’re working on adding more horsepower.
It is genuine, it was announced on Twitter and Facebook.
I was ABOUT to buy it 3 weeks ago and someone unnamed on the forums recommended to wait until GDC for a “potential” discount. Looks like that worked out well
astounding new!!
The 1000$ question;
Is it “free to buy” until April 8th without expiration?
Or is it “free to use” until April 8th and expires then?
Free to buy I assume, Free to use would make no sense as you can already get a 30 day trial of Unity pro iOS/Android at any time.
More than likely it’ll be free to buy until April 8th without expiration. After all, you are receiving a license key for this, if I read correctly. I’ll let someone that knows better than me give a final answer.
Agreed.
Time to upgrade all my Pro+Team licences to Pro+Team+Android Basic+iOS Basic.
if you are lucky to get the store working hahahaha
Got one month to do it. Worst case scenario; I’ll send an email to sales AT unity.com
For every good thing to come around, there’s always someone ready to complain. You bought it for $400 because you felt it was worth that much to you.