Here's the list of changes since 3.4.2. http://lists.dragonflybsd.org/pipermail/commits/2013-August/197955.html
The 3.4.3 images are up on dragonflybsd.org and will be on mirrors over the next few days. If you've already got DragonFly installed, cd to /usr and 'make src-update' should get you the latest code, and then follow /usr/src/UPDATING to rebuild world and kernel.
