Am I missing something or are these just regular Kaggle competitions, but with no prizes? What is google offering, other than the branding? Why are competitors motivated to take part?
There is often beauty in good competition problems. And you can even learn something along the way.
Google seems to have skipped out on the prize and substituted branding
At the same time at least Google Code Jam which I participated in, is an event for the masses where while there are winners in the end the focus is on great experience of thousands students and recreationals who participate.