These are some of the best VCP4 Study Materials from VMware and other blogs; this can be useful for reference and study for the VCP4 certification.
VCP4 Exam Blue print
VMware Official Documentation for vSphere
VMware vSphere 4 Documentation
Consolidated Backup Documentation
vCenter Update Manager Documentation
vCenter Converter Documentation
Study materials
Learning guide by Matthijs van den Berg
VCP4 vSphere Study Notes from Simon long’s blog
VCP vSphere 4 Practice Exams from Simon long’s blog
vSphere 4 Mock Exam from VMware
Test the VMware General IT Knowledge
Related Blogs
http://www.yellow-bricks.com/2009/11/14/vcp-4-exam
http://www.simonlong.co.uk/blog/vcp-vsphere-4-practice-exam
http://www.simonlong.co.uk/blog/vcp-vsphere-upgrade-study-notes
http://professionalvmware.com/2009/07/vsphere-vcp4-beta-follow-up
http://vmwaretraining.blogspot.com/2009/09/studying-for-vcp-on-vsphere-4.html