I find it hard to believe that you did not anticipate exactly this happening when designing (a) an online file backup service, (b) a "de"-duplication algorithm. That said, you should have planned for exactly this a long time ago, whether by the means DropShip used, or any of several other potential file sharing hacks. I think a lot of us here are disappointed with how your actions reflect that planning, or lack thereof.
I agree. I actually proposed this idea a while back but never went through with the implementation. I hope Dropbox turns a blind eye to this because I think its fair use of Dropbox. Instead of someone sending you the file and then you adding it to Dropbox manually, you can just send the hash for the file and receive without P2P. This is where the world of online storage might head anyways.
I find it hard to believe that you did not anticipate exactly this happening when designing (a) an online file backup service, (b) a "de"-duplication algorithm. That said, you should have planned for exactly this a long time ago, whether by the means DropShip used, or any of several other potential file sharing hacks. I think a lot of us here are disappointed with how your actions reflect that planning, or lack thereof.