I suggest using a continuous (or at least nightly) build strategy.
Rebuild the database on every checkin, or at least once per day.
Also once per day, run unit tests to exercise each bit of code, be it in a stored procedur, a trigger or a data access layer.
There is a great cost to writing stored procs, but this will identify breaks immediately.
Once you know where the break is, you can fix it.
I'd be interested to hear other people's experiences with this strategy applied to database changes.
