I see traditional email and newsgroup clients missing a bit from
Krinkle's list. Subthreading works perfectly fine in Thunderbird (but
even in Outlook Express!). Indenting is the one characteristic found in
all wiki conversations: subthreading can't be discarded based on gut
feelings.
In my experience shepherding thousands of it.wiki conversations (mostly
on their own subpages), the biggest issue are offtopic and personal
tangents, hence the most important technical feature in wikitext is that
I'm able to easily tell apart, link and move subthreads.
Nemo