I would also love to see "official" support for these types.

One thing to consider is how to persist the currency of MonetaryAmounts. Jadira supports persisting just the amount with a fixed currency parameter (not stored in the database); or persisting the MonetaryAmount as two columns. (http://jadira.sourceforge.net/usertype-userguide.html)

A third option would be to persist amount and currency as a single string column with some separator character.