On the Ibuildings techPortal today there's a new post from Robert Raszczynski about domain modeling and how a good knowledge of it can help your application's architecture.

Architectural and design patterns help software architects to break systems in to smaller, more maintainable sections organised by their functionality and usage. [...] There are three major layers in software architecture: presentation, domain and data source. [...] Now that we know what types of layers we can find in software architecture, let's have a look at how we can organize domain logic and data sources layers.

He looks at three patterns that can help organize your domain logic - a transactional script (one file that does one thing), a table module (logic lives in the tables) and his focus, the domain model. He shows (via a graph) how the domain logic approach can cut through some of the effort it could take to improve on the other two. He gives a two suggestions of how to access the data in your domain layer - a Gateway or a Data Mapper. To reinforce the ideas he's presented, he includes some code snippets of a basic domain model for a Store, Customer and Product and uses them in both Gateway and Data Mapper examples.