This question describes how to get the changelog for a given package. However, it's the whole changelog.
What I'd like is a way to see what will be changed in whatever I'm about to upgrade. For example, I was imagining something like:
$ sudo apt-get upgrade --show-changelogs
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
The following packages will be upgraded:
foo
-- adds the bar feature for better snazziness
-- removes the deprecated baz feature
1 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
Need to get 8,864 kB of archives.
After this operation, 285 kB disk space will be freed.
Do you want to continue [Y/n]?
Unfortunately, I don't see anything like that in the man pages for apt-get. Does this or something similar exist?
UPDATE: I've written a short blog post talking about apt-listchanges and Debian changelogs in a little more depth that incorporates some of the feedback in this question.