Work in progress, I'll write this up properly when I'm done.
Almost all credit goes to @maxogden for putting me on to this and pointing me in the right direction for each of these items.
- Raspberry Pi
- Kindle Paperwhite freed from its locked down state (jailbroken) http://www.mobileread.com/forums/showthread.php?t=198446
- You have to downgrade your Kindle to 5.3.1 to install the current jailbreak; that's just a matter of getting the old version image, putting it on your Kindle via USB and telling it to install "upgrade". Then you put in the Jailbreak files, load the ebook and break.
- Your kindle will be quick to detect an upgrade is available so it'll want to upgrade soon afterwards but the jailbreak will last but you have to reinstall the developer certificates so it's a bit of a pain but doable. Find all the instructions on the mobileread.com forums and wiki.