At last, here is Android Lollipop for BeagleBone Black!
This is a "work in progress" so don't expect everything to go smoothly. I have tested this build on a BBB rev A (2 GiB internal eMMC) and a LCD4 cape. Here are some issues that I have found up to now (please report any other odd behaviour you find):
1. The graphics are not accelerated and the screen flickers whenever it is updated
2. The initial boot time is long, expect to wait several minutes
3. The buttons on the LCD4 cape do not work
4. The Ethernet interface is not configured
5. The Linux 3.2 kernel is unreliable if built with the gcc 4.8 toolchain that comes with AOSP 5.x
For those of you who want to build from source, the device configuration files and information about building are at https://github.com/csimmonds/bbb-android-device-files/tree/lollipop-5.1
I have also uploaded a pre-built micro SD card image, which you can get from http://2net.co.uk/downloads/bbb-android/BBB-aosp-5.1.0-sd-img-2015-06-29.zip".
To write it to microSD, plug card of at least 2 GiB capacity into your card reader: it will show up as something like /dev/mmcblk0 or /dev/sdc. Make absolutely sure that you know which it is before continuing because hard drives also show up as /dev/sd* and writing this image to your hard drive will make your computer unbootable!. Assuming that the card reader is mmcblk0, write the image using a command like this:
$ sudo sh -c "unzip -p BBB-aosp-4.4.4_r1-sd-img.zip | dd of=/dev/mmcblk0 bs=4M"
Plug it into your BeagleBone Black and boot it up.