They have posted the XNA Zune FAQ:
Q: Will this feature only work on newer Zune devices?
A: XNA Game Studio 3.0 currently will support Zune 4/8, Zune 30, and Zune 80 devices.
Q: Can I build ccgame files to share my Zune game with my friends?
A: The XNA Game Studio 3.0 preview will not support sharing CCGame files with other users. This is a planned feature for the release.
Q: Can I transmit the game to another Zune device wirelessly?
A: No, you must deploy the game to your Zune through your device connection on your PC, using XNA Game Studio 3.0 to deploy.
Q: Do I need an XNA Creators Club subscription to deploy the game?
A: No subscription is required to deploy the Zune game from your PC.
Q: How does the wireless support work?
A: The Zune device can support multiple Zunes that have wireless turned on. If all the Zunes have the game deployed, and the game is written to work in a multiplayer mode, you can join in and play games with other Zunes.
Q: Are there any limitations on how I can use the music that’s stored on the Zune
A: Any DRM licensed music cannot be played; otherwise you have full access to the music and pictures stored on the Zune.
Q: You mention the Zune will be supported in XNA Game Studio 3.0, what else is supported in XNA Game Studio 3.0?
A: We have not announced any other features for XNA Game Studio 3.0 at this time.
Q: Will XNA Game Studio 3.0 work with Visual Studio 2008?
A: Yes, XNA Game Studio 3.0 will only work with Visual Studio 2008 and Express 2008 SKUs.
Q: When will we be able to try this feature out?
A: We expect to have a preivew of XNA Game Studio 3.0 available in the spring.
Q: What kind of gameplay limitations do I have?
A: With a 240x320 display and a design for one-handed usage, building games on the Zune requires some creative thinking that aligns better with mobile games. The XNA Community Game Platform team has worked hard to give you the broadest access to the XNA Framework API.
Q: Is the full XNA Framework Graphics API available on Zune?
A: No, The Zune supports 2D graphics through the XNA Framework SpriteBatch API’s. Rendertargets and the ability to directly set pixel data to textures enables developers to be creative with their Zune games.
Q: How much memory is available for Zune games?
A: Games on Zune are limited to 16Mb for code and content.
Q: Does the Zune support Xbox LIVE?
A: No, the Zune doesn’t connectto Xbox LIVE. All networking takes place over a local ad-hoc wi-fi network. However, the networking APIs are similar to what is available in XNA Game Studio 2.0.