There is a library for JodaTime that provides Hibernate persistence. Recently I started looking at Joda-Money and started to see how that can be persisted using hibernate and I
The User Type project provides support for joda-money 0.6 since version 3.0.0. Please note however that this requires Hibernate 4. Also the current joda-money version is 0.8
If you want to use it with Hibernate 3 use the example in Sudarshan anwser (it's bugged at the time of writing).