This stuff is both great and depressing. The problem is that some companies, like Google, 37signals, etc. let their workers do these kinds of projects. Yes, some of them will bring those companies more customers, but the reality is that it's not clear if the hours put into this type of thing will ever pay off. Despite that, these companies can afford to have 20% time, or whatever it is, and let their employees mess a…
This is not new, in the 1950s HP and 3M employees had respectively 10% and 15% time. The post-it was invented during this 15% time at 3M. http://www.codinghorror.com/blog/2012/08/today-is-goof-off-a...
This gets tricky with companies that are no longer startups, but are not the 800 lb gorilla in their space either. Do you derive more efficiency from fostering X% time, or by getting your team to focus on the problem at hand?
I suppose that in the end, if your team is unhappy with the overall direction of your company, throwing them an occasional carrot will not fix things. You need to actually fix the underlying problem.