Four months of struggling with fragmented business layers have helped me to understand through experience what I already knew in theory: placing business logic in stored procedures without a valid reason is simply bad! For systems that are deployed once and then left alone this could be fine! But for those systems where the business rules and the developers involved change frequently this can lead to a codebase that is a nightmare to deal with! Here are a few links that tell you why:
Business Logic in Stored Procedures is bad!