Today I visited a session on entity framework. Lots of cool new stuff in .NET 4.0, finally we get poco objects. And as a matter of fact there is a new feature available as of today in an additional download with even more improvements, like generating your poco objects from the edmx model. The best part is you can change the way code is generated by editing the T4 templates in VS2010. This way it is finally possible to create a testible datalayer without importing all the EF stuff. The EF team also created classes to support offline changing of objects, like you could in the dataset days (remember diffgrams?). This is particulairly good when you send your objects over the wire with WCF. When you send the changed object back, the host can reconnect your entity to the datacontext and apply the correct actions on the datastore.