So basically on the Kindle they offer new software updates and it will give you things like new fonts?
With the latest K2/DX software upgrade to 2.5.x, we may not have the ability to install font "hacks" anymore, as it appears Amazon has plugged the "hole" in the software that allowed those hacks to be installed. However, they are in the process of rolling out a software development kit (SDK) to allow 3rd party programmers to create/sell Kindle applications, which
maybe at some point will include the same sort of unofficial font and screen-saver hacks many of us have become accustomed to. But that's all speculation at this point.
If you were to go with a used K1 as you discussed in another thread, it already has an ability to change the screen-saver images, but to the best of my knowledge no way to load other fonts.