Since Opera first introduced their Speed Dial page, other browser makers integrated this feature into their products in various forms. Chrome developed the idea by introducing web apps and the most visited pages into the picture and for all other browsers there had been a flurry of extensions that more or less did the same.
Now, Mozilla's UX team took it upon themselves to bring Speed Dial to Firefox and you can already check out their work in progress in the latest UX nightly builds. If you want to test it, my advice is to just install it into a virtual machine as these builds aren't guaranteed to be stable.
For now, you get 3 by 3 list of your most recent pages, which you can pin or rearrange to your heart's content. Also, there is a small icon in the top right corner if you want to disable this feature.
At the same time, the home page has received a minor overhaul. Now, it gives you quick access to your bookmarks, history, settings, add-ons and downloads with one click.