From their website (https://www.readability.com/learn-more/):
Readability works on all major phones and tablets. It detects your device and optimizes your reading view for maximum comfort.
Arc90 is also working with Marco Arment (founder of one of my favorite web services - Instapaper) to create a Readability app for iOS devices. In addition to creating the app, Marco is an advisor for Arc90 about the Readability service so you know it will be good. You can read Marco's blog post about his involvement with Readability here, http://www.marco.org/3044068415.
In order to make it easy for you to use Readability, I've discretely added the Readability button underneath the post header for all individual posts and pages. Since Readability isn't designed to work on main collection pages, the main page of this blog will not contain Readability links. So if you want to try out Readability, click on the the title of any blog post to visit that individual article. Then simply click on "Read: Now" to see that article optimized for your reading pleasure by Readability. If you like it, consider joining to support future development of the service and to support content creators - including me!