What if they allowed duplicate names? Navigating to twitter.com/username would then display everyone with that name (like how Wikipedia handles it). The chances that you are following more than one person with the same name is pretty slim. If that does happen, then you pick which one gets your @ replies.

I wouldn't want my competitors sharing a username with me.

Because you worry there wouldn't be a unique way to link to you, or because you don't want your potential customers to know who thinks they're your competitor, or because you're worried people would get confused?

that's a good point, but i bet that could be resolved, too. i like the show_all option. the more transparency the better. we still want to be careful not to squander the resources of clarity and lack of information.

One solution is to expose unique IDs and allow people to hang nicks on those. Using email addresses or phone numbers goes most of the way toward this (it's not all the way, since people could get an email address or phone number that someone else used to have, at some ISPs or phone companies). However, there's a larger, related problem, which is the problem of identity: there is no foolproof way of identifying individuals, and the more you investigate, the more clear it becomes that existing attempts fail miserably for edge cases, and criminal / fraudulent activity is probably the longest edge.

Isn't it the same issue as last year, and the last 10 years? Picking usernames etc isn't a new practice.

My point is that it's an old problem in desperate search of a solution. We need a single name that works across all sites. Why should I have to tell people that I'm AndrewWarner on Hacker news and Twitter, but if they want to find me on digg on AndrewDiggs because AndrewWarner was already taken. And if the want to find me...

We need one public identifier that works across all networks.

What do you think?

Solve it the same way that they solve naming conflicts in programming languages: namespaces (Edit: as others have suggested).

There is both a "whitehouse.com" (it has a landing page at the moment, SFW) and a "whitehouse.gov"

I tend to side with Twitter here. Don't like it? Go create your own website (set up a laconi.ca node). I don't think that there is any inherent justification in the first-come-first-serve method of provisioning, maybe it is just an artifact of our culture?