One of the best link collections i ever saw related to vSphere 4.1, all the study materials are there for you to start playing with vSphere 4.1.
Eric Siebert done a good job to contribute this much resource in one piece
Archive for VMware
VCP4 exam preparation guides and study materials
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
vSphere reference card
vSphere 4 card and esxtop precis has been recently updated in vreference by Forbes Guthrie, This is one of the useful reference guide for the VMware administrators.