For all the noobs out there this is more inlikely the most easy to ROOT your Eris!!!!!! HAPPY ROOT'INhttp://forum.xda-developers.com/showthread.php?t=742228
I Ripley, have edited to include instructions rewritten for clarification.
Step 1: Download and install the one click apk or get it from the market and install it.http://dl.dropbox.com/u/8699733/erisone010.apk
- VERSION 0.1.0
Step 2: Run one click program, read disclaimer, press button.
Step 3) Reboot into recovery mode. Do this by turning the phone off and then turning it back on by simultaneously holding the Vol Down and Power Button. This will boot you into HTC's white screen HBOOT. You will see the following:
<SEND> FastBoot Mode
<VOL UP> Recovery
Select recovery with volume up button
Step 4: You will see a black screen with green writing(sorry but no time for screenshots today), this is called Android System Recovery, which you will see at the top of the black screen in green. Using Amon's recovery(Android System Recovery) with the trackball to navigate and select, pick the backup/restore option. Then select Nand backup with trackball, press trackball to confirm.
Step 5: Once the backup is complete, press the Vol Down button to return to the main menu.
Step 6: Once back at the main menu, pick "Flash Zip from SDCard" and then select rootme.zip that came with the one click program.
Step 7: Press the Vol Down button to return to the main menu and select "Reboot System Now"
Step 8: Once the phone is re-booted, go to settings>applications>development and turn usb debugging on.
Step 9: I would suggest getting quickboot from the market. This will make flashing a new rom of your choice much faster.
Thanks to Jcase and PRJ.