I agree with OcularInk. Like they said, "Great minds think alike" ;-)
It is very difficult to come up with one very unique logo idea that hasn't been thought of by another person somewhere on this big wide world.
My apologies, 38one. But that is the first time I've seen this design you linked too. Stairs are stairs. You cannot trademark a concept like that. If you position the designs on top of one another, they are surely different. I certainly commend the original designer for his/her incredible work.
The reality is there is no way for me to be aware of all of the logos, symbols, and concepts out there, no matter how high-profile the logos are. Sometimes great ideas arise simultaneously from several independent minds. In this case, that is what happened.
The logos will be used in completely different markets so I don't see an issue. I will continue to strive to create new and unique solutions to my greatest ability. But surely, this is bound to happen from time to time.
Great!