The answer above is incomplete: if you're like me, you're here because you have found yourself using some script (perhaps a "configure" script) that parses the output of udevinfo to ensure that udev is recent enough.
In that case, the arguments to "udevadm info" and "udevinfo" might be the same, but the output isn't. For me, it was enough to replace the original line:
udev_ver=`udevinfo -V | awk '{ print $3 }'`
with
udev_ver=udevadm info -V | awk '{ print $1 }'
The script with this modification ran without errors, and I was able to get on with the rest of my life :).