I do have a droid 3, and have been waiting anxiously for a rooting mechanism. Yesterday, when someone on a mailing list I frequent posted a link to a forum announcing a droid 3 root, I had to get in on it. But the mechanism was in the form of a Windows binary-only application. Below the link were several people complaining that the file was tripping up their antivirus software. Running strings on the file, I was able to see that it was creating outgoing TCP connections to port 6667 (IRC). You do the math on that one. I was also able to extract the rooting method, though, and I’ll reproduce what I did for others:

Run “adb shell” on a computer connected to the droid to enter these commands.

mv /data/local/12m /data/local/12m.bak
ln -s /data /data/local/12m

Now, reboot the phone. When it comes back up, adb shell into it again and run:

rm /data/local/12m
mv /data/local/12m.bak /data/local/12m
mv /data/local.prop /data/local.prop.bak
echo ro.sys.atvc_allow_netmon_usb=0 > /data/local.prop
echo ro.sys.atvc_allow_netmon_ih=0 >> /data/local.prop
echo ro.sys.atvc_allow_res_core=0 >> /data/local.prop
echo ro.sys.atvc_allow_res_panic=0 >> /data/local.prop
echo ro.sys.atvc_allow_all_adb=1 >> /data/local.prop
echo ro.sys.atvc_allow_all_core=0 >> /data/local.prop
echo ro.sys.atvc_allow_efem=0 >> /data/local.prop
echo ro.sys.atvc_allow_bp_log=0 >> /data/local.prop
echo ro.sys.atvc_allow_ap_mot_log=0 >> /data/local.prop
echo ro.sys.atvc_allow_gki_log=0 >> /data/local.prop

Reboot the phone again. When it comes back up, adb to it a third time, but this time notice that you have a root prompt! Setting atvc_allow_all_adb to 1 disallows adb from dropping its root privileges. Now, to make this accessible to the device, run:

mount -o remount,rw /dev/block/system /system
cat /system/bin/sh > /system/xbin/su
chmod 4755 /system/xbin/su

Now, go into the market and search for the “superuser” application. Install the one with the jolly-rogerish logo, then run it and have it install its su binary. Once that’s done, we need to remove the su application we created, so in the adb shell you still have open, run:

rm /system/xbin/su
mount -o remount,ro /dev/block/system /system
sync

That’s it! You’re all set. Enjoy having root on the droid 3!