In WordPress 3.5 all of the GD functionality has been abstracted out and with that power Imagick has been including to WordPress 3.5 too. Gmagick needs to wait a little bit more but with this plugin you can already use it.
If you want to know a little bit more about the changes you can look at:
- Sync with WordPress 3.9 and 4.0
- Checking if we always dealing with Gmagick objects
- Small bugfix after WordPress 3.8 when setting quality could end up not working
- Fix loading gmagick only once
- First version