The Exchange Server 2007 Beta 2 SDK is out!
You can get it from here - https://www.microsoft.com/downloads/details.aspx?FamilyID=8c32d5ee-a071-459e-843d-8ede0a9582b3&DisplayLang=en
Its got code and samples aplenty~
Bandwidth Logging
Body Conversion
Bridgehead Logging
Calendaring
Cancel Appointment
CDO Scripts
COM Interop
Create Mailbox Before Logon
Create New Appointment
Create New Store
Custom Filter Sink
Events
Gateway Logging
Issue Tracking
Managed Tree View Control
Messaging Samples
Move Mailbox ADSI_CDOEXM
New Mail
Notification
OLEDB Scripts
Security
Task Wizard
Technology Evaluation
Tree View Control
User Information Web Service
WebDAV
XHeader
The following APIs are not available in Exchange 2007:
Collaboration Data Objects for Exchange Management (CDOEXM)
Windows Management Instrumentation (WMI)
Collaboration Data Objects for Exchange Workflow (CDOWF)
Exchange Web Forms
At Functions
Outlook Web Access Customization
Exchange Server 2003 Task Wizard and the XML files it produced
The following APIs are de-emphasized in Exchange 2007:
OLE DB provider for Exchange Server (EXOLEDB)
Collaboration Data Objects for Exchange 2000 Server (CDOEX)
Web Distributed Authoring and Versioning (WebDAV)
Exchange Store Events
Enjoy...