If your Android application is targeting specific hardware, you may be interested to know that we've worked with a number of ARM based SoCs that are great choices for Android embedded systems: the Freescale iMX53, Texas Instruments' Sitara AM335x and Qualcomm's Snapdragon. The AM3358 is the most popular choice because of it's very high capability to cost ratio, but each project is different and you may need something else. In some cases you might need an Android device driver developed, which of course would really be a Linux device driver, but that's rare. Most of the time you can run with the Android port and Linux kernel version that comes with the SoC manufacturer's evaluation board and sometimes even the hardware reference design won't need much changing to make your idea production ready. In addtion to Android we can also work with Keil RTX, ThreadX/GUIX, QNX and FreeRTOS - and who knows we've probably got an eval board lying around to start working on your project now!