Yes, the black and white one! thanks Arjen.
The reason i'm interested in it is because the solution might resurface soon enough. Can't say more about it, unfortunately.
It already has, multiple times. There was a report produced earlier this year, joint NASA-DARPA (and I think USAF) study that looked into air-launching rockets off the top of a 747. You can find that in the space section. I think the proposal was to use one of the leftover Shuttle Carrier Aircraft.
I did a bunch of articles on the vehicle in the image above that you're interested in:http://www.thespacereview.com/article/1608/1
There's even an AIAA paper on the Rockwell proposal. They initially considered a Space Shuttle Main Engine in the tail of the 747, then switched (if I remember correctly) to multiple RL-10s, which gave them more ability to throttle. It's all in those articles.