Yes, once the KMS host is activated, it is able to activate Project and Visio 2010.
To be activated using KMS, volume licensed version is required.
For your reference:
Volume activation quick start guide for Office 2010
The detailed steps for activation that are listed in the scenarios apply to all Volume License editions of Office 2010 client products (Office Professional Plus 2010, Visio 2010, and Project 2010).
http://technet.microsoft.com/en-us/library/ee624359
Max Meng
TechNet Community Support
