This is already possible and used by some apps. If you use eSteem to post, 5% of your post's reward actually goes to @esteem.
It should be possible to create some kind of app where you can set all the beneficiaries before posting something, so that you can share the reward.
Nice idea, this feature can be quite powerful if used right!
I have never used esteem either. I think it would be interesting to see how it could change curation and project team dynamics. I would be interested also in being able to give a little to some members I think deserve it but don't get it. It is hard to keep track manually.