Finally Microsoft has decided to release to a small number of partners the first bits of Microsoft Dynamics CRM code-name "Tytan", the next generation of its CRM suite.
This is the news that we was waiting. MS Dynamics products are always too much secret under their beta stages and this is not always a great choice... as Windows Vista and Visual Studio can teach us, working closely with the communities in order to receive feedbacks and suggestions is the key to have a product that rocks!
I hope that this will be the right direction not only for CRM, but also for other Dynamics products such as (for example) Dynamics NAV 5. We all know that NAV 5 will be a revolution, but actually we can't test if we're ready for its coming. 
Remaining "on topic", Microsoft CRM 4.0 will be the first Dynamics product to offer a new concept of service: it will offer an on-premise and a Software-as-a-service (SaaS) version that will use a single code base and metadata model on a multi-tenant architecture (multicompany).
This new architecture will permit customers to switch from one version to another as needed during the years, so they can start for example with a hosted CRM with basic features and, if their business needs grow, they can choose to bring the CRM system "in house" and developing their custom solutions... all in a total freedom. 
Wonderful, isn't it?