We've seen Android run on anything from low-resolution smartwatches to high-PPI phones and tablets, including the new 1920 x 1200-pixel Nexus 7 Google launched earlier this week. To make this possible, the mobile OS supports a number of pixel densities for app content -- from 120PPI (LDPI / Low DPI) to 480PPI (XXHDPI / Extra Extra High DPI). Close examination of the Android 4.3 (Jelly Bean) source code reveals the addition of a 640PPI (XXXHDPI / Extra Extra Extra High DPI) pixel density, which -- according to the comments in the code -- is intended for 4K televisions. Does this mean we'll begin to see Android devices with 640PPI Ultra HD displays? Perhaps, but considering 480PPI is overkill on handsets, this is most likely designed to make image assets and fonts, such as the Google TV UI, readable on 4K screens when viewed from a distance.