Our primary motivation is leveraging an existing code-base and experience for internal functions. For example, we would like to migrate some data logic from our loaders, written in Perl, into triggers. Given some of the complexity in our data, using Perl in the data retrieval would be a blessing, but I am cynical about performance (but not prematurely optimizing).
This is all underscored by a recent security policy handed down severely restricting what we can use as a front end. In particular, all code running between the database and the outside world must be Java or .NET and all custom code is strongly discouraged. I would like to emphasize we are not munging up display and data logic - I'm talking about ranking/grouping, complex constraints, ...