The original upload had a corrupted file in it, but it may have been an intentional joke (read forum). However, the file was repaired and rebuild. As I type this, I'm on page 13 of the forum and at least a few people have confirmed it is REAL.
So, read the forum (the first few pages are about the corruption) and install if you cant wait for the OTA release! I'm going to read the rest of the forum thread and probably do the upgrade in a bit.
Android Communitiy posted a short article here:
http://androidcommunity.com/droid-eris-receives-leaked-android-2-1-20100303/
XDA Forum Thread:
http://forum.xda-developers.com/showthread.php?t=641588&page=1
HowTo (abridged with patched/fixed download):
http://thekrtek.net/
Abridged Instructions:
1) copy downloaded file to SD card via USB (mount SD card). I copied it to the root path
2) shut down
3) press hold volumn-down and then power
4) you'll see the Eris BIOS of sorts finding all zip files and verifing if they contain image files
a) some will say "image not found" or something, but ignore those
Just follow the Eris update instructions and it will promot to reboot a few times.
My update to 2.1 took less then 10 minutes, I'm testing right now, but the update went flawlessly!!!!!!!!
I downloaded from here: http://grense.no/android/android.2.1.droid.eris/PB00IMG.zip