VMware released vSphere 5.1 at September 10. It can be downloaded here.
Also released at September 10 is VMware VMware vCloud Suite 5.1. Download here.
To learn about new features VMware made available a one hour, free online course titled VMware vSphere: What’s New [V 5.1] – Customer Facing. This training course explores new features in VMware vCenter Server 5.1 and VMware ESXi 5.1.
vsphere-land.com has a good selection of links to blogs on vSphere 5.1