And older Zunes, too! But let's talk about the HD: With the new OpenZDK toolkit, developers can make homebrew apps for the Zune HD, and by following a relatively simple set of instructions, you can install them.
First, a little background: Zune and Zune HD homebrew isn't entirely new, but it's never been terribly exciting. It's been possible for some time to install Zune apps created in Microsoft's XNA game development platform, which could be distributed to and installed by regular users, assuming they too had development tools installed. So!
What's happened now is that a group of hackers has released a much more complete toolkit, called OpenZDK, which opens up a whole new range of app development, and tons of new classes of apps:
The first true hack available for the Zune, this makes it possible to, for the first time, run applications directly on top of the Zune firmware, with full access to everything XNA withheld before. The limitations of XNA are now no limitations at all.
As OpenZDK has just been released, few apps have yet been built on it. While only time will tell what developers actually create, the door to emulators, homebrew 3D games, ports of classic games, app stores, and much more has now been opened.
Since the toolset is brand new, there really aren't any OpenZDK apps available yet. But there are plenty of XNA-developed apps for you to practice the installation routine with, and a forum prepped and ready to accept submissions, as soon as they're ready. The installation routine goes something like this:
• Install the necessary components of XNA Game studio, [Details]
• Add your Zune to your Device Center [Details]
• Run the Exploit Development Tool [Details]
• Download OpenZDK
• Install applications [Details]
There's no Cydia-style central repository for apps yet, nor is there any proof that OpenZDK will result in anything beyond a few tech demos, but the potential here is huge: a healthy homebrew community could morph the Zune HD from a piece of semi-doomed hardware with abandonment issues to a legitimately interesting app platform, or at the very least, the tweakers' media player of choice. [Zuneboards]