Ah, appears we're both correct: http://en.wikipedia.org/wiki/Walled_garden_(technology)

"... refers to a carrier or service provider's control over applications, content, and media on platforms..."

"More generally ... refers to a closed or exclusive set of information services provided for users"

No, i actually think just he's correct. It's OK to be wrong though, so no big deal.

Though I do disagree with his sentiment. I think App.Net is a perfectly good alternative to Twitter and every attempt at open, federated services since the original one (eg www) have failed to catch-on.

www was not the original federated service. E-mail is still around and quite successful.

Usenet is dead now, but worked for quite some time.