I recently rooted my Droid X and everything seems to be working perfectly. I made some changes to
adb push build.prop /system/
failed to copy 'c:\build.prop' to '/system//build.prop': Read-only file system
Got this off an Android forum where I asked the same question. Hope this helps somebody else.
On a terminal emulator on the phone:
mount -o rw,remount -t yaffs2 /dev/block/mtdblock3 /system
Then on the cmd prompt, do the