Adding Custom Blocks to a Bukkit Server

Hello again Bukkit Community,

I think that my old thread was to complitcated and didn't show exactely where I have problems, so this is a more general thread.

As the title already says it's about custom blocks on a bukkit server and my question is simply: how?

I know that there are some plugins that support that, e.g. ItemCraft, but I want to understand it and I don't want to have more than I want to.

I should add that I'm new to Minecraft and the Bukkit Server Mod

Hopefully you can help me,
R4ID3R

 

Subscribing, I am having a look at the ItemCraft sources, that makes much more than this, and it is quite complicated to understand what is going on.
A basic working example of adding a new block type in bukkit would be really interesting, as a lot of servers are using their own patcher now.