I went through the current codebase and made quite a few changes. These changes brought it up to the standards for CloudFiles and PSR2 formatting.
You can view the code at:
https://github.com/giftcards/rackspace-cloudfiles-cdn
I tried to send a PR, but found that the clone (https://github.com/wp-plugins/rackspace-cloudfiles-cdn) was actually a read only instance of the repository and not maintained by you.
Let me know if you have any questions, as it stands right now your code doesn’t set the correct headers for images. Plus, we really need to consider how to handle when OpenCloud updates. The plugin is well out of date from it (they are up to 1.9.3).
Lastly, I implemented the ability to be notified from WordPress when it had to “crunch” the image to make smaller ones. It will upload the main one they upload, and then find the scaled versions and send those to CloudFiles as well. It bypasses the need to upload everything to CloudFiles initially.
Tested with:
Multi-site (5 sites)
WordPress 3.5
Single file upload
Multiple file upload
Large images, single and batch that are scaled
Small images, single and batch that are not scaled
Read the last commit and I explained what I had to change.