(Doh, I lost this one in my queue, hence its tardiness)
It’s too bad his comments are gone, because this “response” to his piece on microformats doesn’t exactly warrant a separate blog entry. But here it is anyway.
Regarding extensibility, I think the “middle name” issue Dave has is really with the vCard format, from whence hCard inherits its descriptive semantics (i.e. vCard has no concept of “middle name”, only “additional names” – hCard has support for this via the *-Name classes, though I admit it’s underspecified). IMO, the microformat approach in general, has a very good extensibility story; extension classes are ignored, while extended content is ignored by automata, but rendered to humans. Plus there’s also a nice hack for cases where machine-processability gets in the way of human-friendliness; “display: none” in CSS.
In fact, thinking about it some more now, I think the bulk of the innovation in (and coolness of) microformats is exactly that it works within the constraints of existing extensibility points in a pervasively deployed format. Anybody can invent a new format, but it takes genius to reuse an existing one.