The HTC Droid Eris root is only for Android 1.5 devices right now. If you use it for anything else, you might brick your phone. Instructions for rooting the Droid Eris can be found at the thefuzz4.net site.
The root for Droid Eris will update the OS to the latest version aka, Android 2.1. Users who run the root will not be able to rollback to Android 1.5 with the current root. Please make sure to backup your phone data and applications before you root the Droid Eris.
Disclaimer: We are not responsible if you brick your device, so root at your own risk.
[via Android Forums]