Version Control for Graphics
Solution 1:
Yes, having art assets in version control is very useful. You get the ability to track history, roll back changes, and you have a single source to do backups with. Keep in mind that art assets are MUCH larger so your server needs to have lots of disk space & network bandwidth.
I've had success with using perforce on very large projects (+100 GB), however we had to wrap access to the version control server with something a little more artist friendly.
I've heard some good things about Alienbrain as well, it does seem to have a very slick UI.
Solution 2:
GitHub recently introduced "image view modes", take a look: https://github.com/blog/817-behold-image-view-modes.
Solution 3:
We, too, just put the binaries in source control. We use Git, but it would apply just as well to Subversion.
One suggestion I have is to use SVGs where possible, because you can see actual differences. With binaries (most other image formats), the best you can get is a version history.