There is an updated version of the Project SDK:
Project 2007 SDK online
Project 2007 SDK download
New and updated topics since last April's release include:
· Task Start and Finish Dates
· Extending the Project Workspace Template
· SetAssignmentWorkData Schema Reference
· Changes for Custom Project Guides (additional information for deployment)
· Using the Project.Open Event
In addition, there is more information and examples for the Queue and the event receiver methods, along with several documentation bug fixes in other PSI reference topics.
The download also includes an updated XML schema reference for Project Standard and Project Professional (mspdi_pj12.xsd), and a redistribution license for the Microsoft.Office.Project.Server.Library.dll assembly.