The last copuple of months I have been building a SharePoint 2010 solution using SPMetal (LinqToSharePoint) and the SharePoint Lists as model layer.
The cool part is, that it can be deployed as one SharePoint sitedefintion. No need to create and connect to seperate applikation databases. It's all SharePoint ;)
the not so cool part is, that we rely entirely on the SharePoint engine to handle the model layer. Depending on your code and requirements performance is a potentiel issue. So remember to do early technological proofs if you try to build it this way.
Michael Høtoft
af81e7c6-08ad-416e-b53f-db52a5e1b6f0|0|.0
Sharepoint Server
SharePoint 2010, SharePoint, Solution Architecture