SDX forum members have tested the ROM out and found it working, with the exception of some of them not being able to log into the Market. A phone reset reportedly fixes this problem. Of course, proceed at your own risk.
The leaked ROM comes after Sprint earlier this week reportedly began internal testing of Android 2.1 on the Moment by releasing it to some of its employees.
Here is the ROM information from the leak:
firmware version: 2.1-update1
baseband version: s:m900.8.os.dd03
kernel version: 2.6.29
build number: elcair.dd03
Update: here is a video of Moment with Android 2.1 and some live wallpaper action: