As we all know, the general rule with open source software is that it is distributed for free. The idea being that the work the community puts into the platform will off-set money needed to pay workers. Of course, freely distributed doesn't mean it isn't a good idea to accept donations, which Canonical now does when you go to download Ubuntu.
There is now a form that will allow you to donate however much you would like (and donation is completely optional) when downloading Ubuntu, but the interesting part is that you are given sliders to adjust where you'd like your donation to go, much like how Humble Bundle handles its donations. You will now be able to donate and direct your money to options like improving gaming, better variants like Kubuntu or Xubuntu, or even "phone and tablet versions of Ubuntu
So, if you have always wanted Ubuntu on your mobile device, and not just the Ubuntu for Android system, you can vote for that to happen with your donation dollars. Of course, if you'd like to just download Ubuntu for free, you can still do that as well.