Many people are now trying to surf the wave of ‘open’ and that seems to annoy Chris Messina. The idea is abused, no doubt about it — however, the argument that ‘Open’ is clearly defined, or fully beneficial isn’t true either. Social networks are not a simple product: they are composed on many elements, and opening always focuses on a limited set of those features. More generally, the proper angle to adress ‘opening’ is either from an CS point of view: what is feasible; or, rather from an economic point of view: what is made easier, cheaper to do?
Communication studies have described more interactions between platforms through three types of efforts: switching (changing provider) multi-homing (having several provider) and roaming (reaching someone on a different provider). DataPortability encourages switching; most projects, especially OpenSocial, multi-homing; DiSo is the only effort that adressses most features of a social network and offers cheaper roaming. Facebook Connect still demands that you have an account and abide by Facebook TOS — and so should your friends who want to communicate with you. I still have no way to share my Facebook-generated feeds with people who refuse to subscribe to the site.
I’m not saying the site doesn’t offer amazing features, on the contrary: they offer a great service — the only way to reach a monopoly with a free service. I’m saying that, by making it easier to go from another SNS to Facebook (or any other monopoly) one is not helping struggling sites, but giving arguments to consider the largest site, the one likely to end up being the only one around, rather then the on with the features that match the niche needs or you and a few of your friends. Same for multi-homing: language studies have repeatedy proven how by having everybody speak two languages: English and another, native one, you end up having all the conversation in English, and loose the useless one; similarly, if everyone is on Facebook and another SNS, say a professionally-oriented one, rapidly, the relevance of the other one fades — and, from apparently evenly shares, the market clicks into a monopoly.
Roaming — ie. befriending people outside of the walled-garden of a given SNS, without having to subscribe to each, and give both rights over your data — allow you to test your own version of any given open SNS, tweak it and innovate. Without that feature, any open code for SNS will be useless: who’d subscribe to a SNS without friends? Who’d contribute code to a project with no rational users?
More importanly, being open, as in ‘letting do what you want’ neglects that my friends might want something else. I don’t want an openness that let’s me in the dark around those disagreements: I want to know what I’m encouraged to do, I want to have socially-sharable authorisation rules. And that openness, that Facebook has clearly identified, has nothing to do with other forms of Open.
I don’t want calls to Openness, I want clarity — and so far, I haven’t read anyone who was unambiguous about it.
Two Croissants 
Yeah, I agree. I realize that “open” means many things to different people — to the point of being meaningless, like Web 2.0. Still, Camel’s use of the term was outright offensive in every dimension. Hard to say that they were using any of the approximate definitions you cited.
Facebook tends to think of “openness” as being related to making it easier for people to share and publish; less to do with transparency of the service. I would hope that one begets the other, but time will tell.
It’d be great to have a working definition of “open” but unfortunately, like pornography, it tends to be easier to know it when you see it.