I am pleased to announce that we have a software jailbreak for the Paperwhite 2. No cables required and no need to open the device.
NOTE:
THIS SCRIPT IS FOR HACKERS. IF YOU DON'T UNDERSTAND WHAT YOU ARE DOING DON'T USE IT AND USE THE K5+PW1+PW2 JAILBREAK INSTEAD.
The script in the attachment installs a jailbreak script in the kindle user directory. The jailbreak script will be run automatically after the kindle is ejected.
This script must be run in a terminal on a linux system. If you don't have a linux installed you could use a live cd (Ubuntu, Knoppix, etc.)
The script can be used for three different types of jailbreak:
1) open a root shell on the kindle
2) run an arbitrary user script
3) install the K5+PW1+PW2 jailbreak by NiLuJe
The root shell jailbreak is the safest mode since it doesn't change anything on the kindle (but it gives you enough rope to shoot yourself in the foot).
The old Paperwhite1 jailbreak doesn't work out of the on the Paperwhite2, you should use the
jailbreak package for K5+PW1+PW2 by NiLuJe.
This jailbreak should work also on the Paperwhite1, even with firmware versions where the previous kpw_jb.zip is no more working.
See the README for more information.
UPDATE: new version 1.1 which uses the jailbreak package by NiLuJe.