VMware vSphere 5.0 is there. You can download the Software using the links below

VMware ESXi 5.0 (Build 469512)
VMware vCenter 5.0
 (Build 456005)
VMware Data Recovery 2.0
(Build 433157)
vSphere Storage Appliance 1.0
VMware vShield Zones for vSphere 5 (Build 216288)

A key for the ESXi 5.0 Free version can be obtained here

All about how to upgrade your licenses can be found here