NOTICE: I no longer work on the app but a working fork is available here: https://github.com/walles/flickr-uploader The Google Play Store link is: https://play.google.com/store/apps/details?id=com.gmail.walles.johan.flickruploader2
The main benefit of this app over Google+ Instant Upload is the fact that you can upload ONE FREAKING TERABYTE of photos&videos in high resolution for free!
You can download it on Google Play Store: https://play.google.com/store/apps/details?id=com.rafali.flickruploader2
You can fork this project or use the source code for any project. It is licensed under the GPL v2. I just request that you do not blatantly copy the app to republish it on the Play Store. You may however use it as a base to create an uploader to a service other than Flickr. You should just have to republish the source code as the GPL v2 demand.
It uses a few open source libraries:
Follow me on Twitter: https://twitter.com/rafali