Pardon my ignorance, but how big of a deal is this? It seems pretty much anyone can make something a "well-known port". My quick check found at least 5 more (non-Dropbox) ports added today.<p>In any case, I'm sure this can only be good for Dropbox and its users. Congrats to the team!
Is the Dropbox protocol open and has an RFC? If not I think IANA should revise their practices to only allow registration of ports for protocols that do.