Thanks for the write-up, David!
Regarding the standardisation issue, it's significant that the Microformats group (Tantek Celik of Technorati et al) has steered clear of attempting to set standards for exactly the log-jam reason you mention, favouring the adaptation of existing standards. From their wiki:
"The hCard format is a 1:1 representation of the vCard standard, in semantic XHTML."
It seems to me that this may give their approach a relatively fast uptake.
As for the structured content standard vs folksonomy, I think that the two will co-exist, much as Google Base allows, with a set of fields that "ought" to be there (date, time, location etc for an event) and more fields for free-form tags. Then it will be up to the end user - individual, aggregator, search engine - how to search for and present it.
Maybe it's going to be more like mashing than meshing, with individuals (enabled by aggregators and SEs) taking what they want from the structured content and what they want from the tagged content.
For instance, a user searches a music review aggregator for all the reviews of heavy metal gigs in Liverpool in 2005 and automatically also receives a tag cloud with the results. Then they use the tag cloud as a basis for making a new view of the reviews on their personal blog.