Интересные новости, или миникарта от Нотча.

After some internal discussion and general anxiety, we’ve arrived at a
plan for supporting mods. It’s still a bit vague and the details might
change after we’ve run it by our lawyers, but here’s what we want to
do:

* Let players sign up as “mod developers”. This will cost money (edit: no longer costs money!), and
will require you agreeing to a license deal (you only need one per
mod team).
* Mod developers can download the source code from our SVN repository.
As soon as we commit a change, it will be available to all mod
developers, unobfuscated and uncensored.
* Mod developers get a unique certificate for signing their mods. This
means players can see who made what mod and choose to trust individual
developers. The cost of signing up makes sure only serious developers
have access to this certificate.

The rules of the license deal will contain:

* Mods must only be playable by people who have bought Minecraft
* You can’t sell your mods or make money off them unless you’ve got a
separate license deal with us
* The mods must not be malicious (obviously)
* We retain the right to use your mod idea and implement it ourselves
in Minecraft. This is to prevent the situation where we have to avoid
adding a feature just because there’s a mod out there that does
something similar. It’s also great for dealing with bug fixes provided
by the community.

In the long term, we hope this means people will do awesome new things
with the Minecraft engine and play around with it. We want to buy
and/or license good mods and/or total conversions and sell them
ourselves. It’s possible we might have a mod marketplace for selling
and buying mods that fans have written, or we might purchase and
integrate nice mods that fit the main theme of Minecraft.

[edit:]

Just to clear up two things:

The access cost won’t be prohibitively expensive, and if you make a good mod or something else based on the source code, it’s highly likely we will want to license it.