VMware View 5.1 is Now Compatible with vSphere 5.1
VMware have just released a patch for vSphere 5.1 which will now enable clients with VMware View to upgrade their virtual environments to the latest version.
The new patch is applied to the ESXi Hosts.
Alternatively you can download the latest ESXi 5.1 ISO from the VMware website.
As with all upgrades, check the compatibility lists before applying and make sure you have a verified backup.