Apt-get upgrade for security announcement

[Eric Walstad <eric@ericwalstad.com>]

Hi All,

I'm having trouble trying to apt-get update/upgrade my debian unstable 
machine with the latest security fixes as advertised in the 
debian-security-announce emails.  When I do:

apt-get update
apt-get upgrade
dpkg -l | grep <package name>

I find that the installed version of the package doesn't match what 
advisory says is available.

In the debian security announcements, the instructions for apt-get 
users say:

-----
For the unstable distribution (sid), CAN-YYYY-NNNN was fixed in
version X.Y.ZZ.

We recommend that you update your <Package Name> package.

Upgrade Instructions
- --------------------
[...]
If you are using the apt-get package manager, use the line for
sources.list as given below:

apt-get update
        will update the internal database
apt-get upgrade
        will install corrected packages

You may use an automated update by adding the resources from the
footer to the proper configuration.
-----

My question: 
1.  The emails imply that there are unstable packages avaialble.  If 
so, how do I apt-get update/upgrade them?

Many thanks for your time and pointers.

Eric.