0.4:

Release date: 2010/10/18

The flag parsing issues of git-flow subcommands are solved for most platforms.
git flow {feature,hotfix,release} finish now takes a -k flag, to keep the branch around after finishing.
git flow release finish takes a -n flag, to skip tagging.
For consistency, git flow {release,hotfix} now, too, have a publish and track subcommand, just like feature.
Various minor fixes.

0.3:

Release date: 2010/07/22

New subcommands for git flow feature:
- checkout:
  For easily checking out features by their short name. Even allows unique prefixes as arguments (see below).
- pull:
  This subcommand allows you to painlessly work on a feature branch together with another peer. This is especially valuable for doing peer reviews of other people's code. For more detailed info, see the commit log.
Easier addressing of branch names by using name prefixes.
For example, when using:

git flow feature finish fo

this automatically finishes the feature branch foobar if that's the only feature branch name starting with fo.
No force flag anymore for new feature branches
git flow feature start lost its -f (force) flag. You now don't have to be in a clean repo anymore to start a new feature branch. This avoids the manual git stash, git flow feature start, git stash pop cycle.
You can use git-flow in stand-alone repo's now.
This means it does not assume you have an origin repository. (Thanks Mark.)
No commands fetch from origin by default anymore.
There were some issues related to disabling this flag on some platforms.
Init guesses branch names you may want to use for develop and master.
Added super-easy installation script. (Thanks Rick.)
Added BSD license.

No change history is recorded for pre-0.3 releases.