The second-generation Apple TV is now shipping, and a few owners who have received their units are having difficulties with sharing and streaming from their Macs. Even though iTunes is set up to share home folders or libraries, the Apple TV is not seeing them on the network even though the previous AppleTV was able to do so on the same network.
Apple does have a few knowledgebase articles available that discuss how to set up and troubleshoot various features of the second-generation Apple TV, so if you are having problems you may wish to read through those. These articles include home sharing setup and troubleshooting, as well as photo screensaver setup.
If you still cannot see the home folder or otherwise connect your Apple TV to your computer after following the instructions in Apple's help articles, then the problem is likely with your computer's configuration and could be from an improper version of iTunes, or issues with your firewall.
Ensure you have iTunes 10.0.1 installed.
When setting up your Apple TV, first be sure to update iTunes to version 10.0.1 (or later), since this version is required for proper compatibility with the new Apple TV. With version 10.0.0 or earlier, you may find that various sharing and streaming connectivity will not work properly.
Reset application firewall.
For the network connections between the Apple TV and iTunes to work, the system's firewall needs to allow the connection. If you have the firewall enabled, be sure you have set the firewall to allow incoming connections for iTunes. To do this, either launch the application and click "Allow" when the system prompts you to set the firewall settings, or go to the "Security" system preferences and add iTunes to the application list, then set it to allow incoming connections.
Another option may be to fully reset the application firewall. If there is corruption in the firewall settings, then doing this can be a quick way to fix it. To reset the firewall, first turn it off in the "Security" system preferences, and then go to the /Macintosh HD/Library/Preferences/ folder and remove the com.apple.alf.plist file. After this is done, you can optionally restart the computer, but then turn on the firewall again.
Do not modify the iTunes program.
We have covered various options for modifying iTunes 10 to add colors back to the sidebar, and though this should not affect the program's functions, some have reported that doing this results in the application firewall continually asking to allow incoming connections for the program. If you allow the connections, they should work, but you may need to do this each time the program is launched for the connections to be properly established, and if you forget to click "Allow" then the Apple TV will not be able to connect.