Now that we have announced the Project Server 2010 and SharePoint Server 2010 Release To Manufacturing (Project 2010 reaches RTM!!!) a great series of assets went live last week to help you plan your 2010 Farm: Capacity Management for SharePoint Server 2010. Since Project Server 2010 is built on top of SharePoint Server 2010 it is key to fully understand how to do SharePoint capacity planning prior to performing Project Server capacity planning, both go hand in hand!
For instance you should all read these whitepapers (both contains Project Server information as well):
Except a lot more documentations in the coming months not to mention the recently delivered webcasts on the subject: Project Server 2010 - Architecture, Sizing, and Capacity Webcast