Linux auto updater reports packages kept back?

On several of my Linux computers recently, after performing an upgrade to the installed packages, I see a category called "Packages Kept Back" that has a few packages in it. Install upgrades nor refresh is able to install them. Perplexing.

The reason: I found a discussion that explained that the updater is intended to only update installed packages. When an update is released that requires installation of dependencies, it is "kept back" to keep the meaning of update pure.

The solution: Running sudo apt-get install on each of the packages kept back will both upgrade that package and install the dependencies, resolving the problem.

The extra-large hammer solution: Running sudo-apt-get dist-upgrade will also resolve these kept-back packages, but will upgrade your distribution as well (for example from Ubuntu 8-10 to Ubuntu 9-04).