With 3.1 released just hours ago, I'll release the jailbreak I wrote (not knowingly) yesterday.
New version without the need for switching update provider, download from link below. Please read readme file.
Thanks to NiLuJe
for the bind keys method.
Both the jailbreak(s) and the source can be found in the link above.
The jailbreak will allow you to install custom packages (hacks) such as the screensaver hack and the usbnetworking hack. It is tested and works on Kindle 3 on 3.1. It should work on all versions of all Kindles from 2.0 to 3.1. No "enable" file needed. No whitelist needed. Just install the jailbreak and you can install both amazon updates and custom hack packages.
If you are using a previous version of the jailbreak or dsmid's change-update-provider hack, it is safe to install this OVER it. Just remember to disable hack updates. (this will be the last time). The 0.4 install removes all previous versions of the update. However, it is recommended that you run the uninstaller.
If you are using NiLuJe 0.5 jailbreak. You do NOT
need this, and the jailbreak WILL fail to install (for protective purposes). However, if you would like to switch, you need to uninstall his jailbreak first.
Comparison to NiLuJe's Jailbreak
There has been much confusion about which jailbreak to use. Here's some clarifications:
-Both achieve the same goal (allowing custom packages), you should not install both at the same time
-Both jailbreaks uses the same method of key swapping
-Both jailbreaks have the same stability and both are uninstallable
-Both are compatible with all versions from 2.X to 3.X, BUT NiLuJe uses different jailbreak methods for older versions while my jailbreak uses the same method.
-NiLuJe's jailbreak implements a whitelist with a hack list that needs to be updated with new hacks.
-My jailbreak is completely transparent (no additional files), but installation of hacks will be 5-15 seconds slower.
0.4: No longer needs ENABLE_HACK_UPDATES file, uses bind mounting, thanks to NiLuJe.
0.3: Uses one file on USB root. If "ENABLE_HACK_UPDATES" exists, use hack keys. If not, use amazon keys. Also uninstalls update-service-provider if installed to prevent conflicts.
0.2: Unofficial test. Modifies updater binary to accept all signatures. Not recommended. Deprecated.
0.1: Initial jailbreak, beta. Used "jailbreak" folder with files to determine what update provider to use.
If you want to know how the "jailbreak" works, you can see the source or read the writeup I wrote here: http://yifan.lu/2011/02/21/kindle-3-1-jailbreak/
Oh, and thanks to lyric
(and others) for beta testing.