Google claimed that ad blockers violated section 4.4 of its Developer Distribution Agreement, which says:
4.4 Prohibited Actions. You agree that you will not engage in any activity with the Market, including the development or distribution of Products, that interferes with, disrupts, damages, or accesses in an unauthorised manner the devices, servers, networks, or other properties or services of any third party including, but not limited to, Android users, Google or any mobile network operator. You may not use customer information obtained from the Market to sell or distribute Products outside of the Market.One of the apps that was banned from the Play Store was Adblock Plus, made by the same people who develop the immensely popular ad-blocking desktop browser extensions with the same name (Firefox, Chrome, Opera).
The new Android version, since it can no longer be in Google's Play Store, must be sideloaded onto your device. To do so, users simply need to visit this URL and install from there.
The new version of Adblock Plus, once installed, will auto-update.
For those unfamiliar with Adblock Plus on Android, it's not as seemless as on your desktop browser, where in general an installation is seamless, on Android you'll have to set up the proxy by yourself.
While, of course, eschewing ads can be detrimental to the financial health of a website that relies on ads for its income. On the other hand, on a mobile device with a data cap, it can be better for your sanity and bandwidth limits.