Christophe,
Sorry for the confusion, the sample is just a mock-up because we do not have a public facing Postgre server at the moment.
To answer you question Postgre is supported through a Spatial Extension that is located in the DeveloperReferences\SpatialExtensions\PostgreSpatialExtension, or some directory similar. The reason this is not included directly in the main assembly is that it has a dependency on a Postgre DLL and we didn’t want the core to have too many external dependencies especially when only a segment of our users will use Postgre.
Thank you for the observation and we will make sure to make this more obvious in the future. As this is a beta we rely on your insights on things that we as developers cant see because we are so close to the product.
David