After successfully updating my Ubuntu 10.04.02 64-bit VM with the usual:

sudo apt-get update && sudo apt-get upgrade

The message of the day (MOTD) did not reset the number the number of packages that required updating. Mine was stuck on:

30 packages can be updated.
23 updates are security updates.

To remedy this, clear out /etc/motd.tail with this command:

cat /dev/null > /etc/motd.tail

When you login again, all will be right with your MOTD.