I’m listening to the Hanselminutes Podcast; \"StackOverflow uses ASP.NET MVC - Jeff Atwood and his technical team\". During the course of the Podcast they are speaking about SQL
I'd say that SPs aren't maintainable and they don't scale. Ask any developer who's had to add functionality to a SP heavy system. Why have half your logic in a different layer? There's nothing to replace, just don't use 'em.