I have also talked with David Weinberger to have his expert feedback.
As always, he came up with excellent ideas and comments worth reading:
"I think the general idea is good and that something like it will
succeed, but I think it's more likely to come from some huge player,
I'm very interested in seeing how tagging becomes a differentiated space instead of the flat space it is now.
Already people are suggesting using prefixes as de facto category tags. E.g., Global Visions, a Berkman Center project, suggests that you tag blogs that give insight into their countries with a "gv:" tag, as in "gv:ghana."
As these prefixes proliferate, we're going to have the same problem as with the DNS.
What happens when Gelber Vistavision (or some other company) starts tagging its stuff "gv:"?
So, I think it's a huge issue, and I suspect it will be addressed definitively by sites that have the clout to convince taggers to adopt their tag sets.
Alternatively, it's possible that the grassroots will adopt a general purpose tag set before sites like Google do, but if we do, I suspect we'll adopt not a single tag here and there (gv or opinionradar) but a few of them all at once, in relation to one another, e.g., "dc-author:" and "dc-language:" (I say "dc" because the Dublin Core would love for us all to adopt its categories). "