Has anyone heard this usage, from today's paper? I'd never even seen "hive" as a verb, and even when I looked it up the definition doesn't seem to fit the text.

The [Chinese] Communist Party might hive off a big chunk of its $1 trillion stash [of foreign exchange] and invest it abroad on behalf of its citizens, a la Singapore's Government Investment Corporation. ... So why hive off foreign-exchange reserves into a Singapore-style fund?

That wouldn't be an uncommon usage here.

I have heard it often enough but have never bothered to enquire into its pedigree.

I have not seen nor heard that usage before. Seems like maybe it's British?

Apparently it is a British usage. See http://dictionary.reference.com/search?q=hive+off&r=66

quote:

to become transferred from the main body of a commercial or industrial enterprise through the agency of new ownership.