After David I keynote at the EKON9 conference in Frankfurt (Germany), Jason Vokes has laid out the details for Dexter. Tomorrow they might show it, but I'll be on a plane travelling back to Italy. Others have blogged on it and will do it again.
Anyway this is the the list of features I had time to jot down. Notice that there is a long list of features for the Delphi personalities (yest, there is C++ stuff as well):

Developer Productivity

• VCL live guidelines (live snap-to guides for positioning and resizing VCL controls at desing time)
• Live Templates, scriptable and extensible
• Block Completion: automatically ends the blocks you begin
• More refactorings

Quality and Performance

• Fastcode memory manager
• Faster startup time (IDE startup and project load)
• More responsive IDE
• Incorporated QC feedback

.NET Enterprise/Database Application Development

• ECO basics in all editions, with object Relational mapping, transparent persistence, object transactions, managed object cache, class modeling
• New ECO III state machines
• Other new ECO features: domain patterns, oveloaded OCL expressions, improved UML designer...

Database Development

• Win32: new database explorer for dbExpress , new unicode dbexpress platform, new and updated dbexpress drivers
• .NET: new BPD connection pooling, BDP SQL tracing, datahub error reconciliation...

Together for Delphi

• LiveSource class diagramming (two-way modeling: changes in code reflec in model and vicevercsa)
• UML diagram suite (class, use case, sequence, collaboration, state chars, deployment, activity, and component diagrams)
• Design patterns support: get started quickly with industry recognized GOF patterns or add your own
• Audits and metrics: gain insight into your source code
• Document generation: generate documentation from your source code and models

Application Lifecycle Management Integration

• Integrated StarTeam User Experience
• Integrated CaliberRM User Experience
• StarTeam Server Standard Edition (in Enterprise and Architect)

Dexter C++ Personality

• Upgrade to C++ Builder 6
• IDE productivity improvements since D7 (database explorer, history managerm sybc edit...)
• New VCL (updates already in Delphi 7 and 2005)
• Rename Refactoring
• CodeGuard 2006
• Configurable Builds (highly configurable and flexible C++ build options)
• IntraWeb RAD C++ Web App Development
• CORBA support