I always enjoy reading the performance whitepapers. They are usually fairly technical and give you a better understanding of how the products work! All of these are most definitely worth downloading and reading! They been released a couple of days back. Check it out:

• vMotion Architecture, Performance, and Best Practices in VMware vSphere 5

  http://www.vmware.com/resources/techresources/10202

• Understanding Memory Management in VMware vSphere 5

  http://www.vmware.com/resources/techresources/10206

• Performance Implications of Storage I/O Control–Enabled NFS Datastores in VMware vSphere 5

  http://www.vmware.com/resources/techresources/10207

• Microsoft Exchange Server 2010 Performance on vSphere 5

  http://www.vmware.com/resources/techresources/10204

• Zimbra Collaboration Server Performance on VMware vSphere 5

  http://www.vmware.com/resources/techresources/10203

• Host Power Management in VMware vSphere 5

  http://www.vmware.com/resources/techresources/10205

• VMware vCenter Update Manager 5.0 Performance and Best Practices

  http://www.vmware.com/resources/techresources/10208