VMware just introduced the most wanted license upgrade from a GSX Server license to an ESX Server + VSMP + VirtualCenter Agent + VMotion, the so called bVirtual Infrastructure Node or VIN bundle package. Customers will be able to upgrade just paying the price difference between two commecial offers.
Quoting from official announcement:
We are pleased to announce that you can now upgrade your VMware GSX Server software to the ESX Server Virtual Infrastructure Node. For the first time, VMware is offering upgrades to our most capable virtual infrastructure product. The ESX Server Virtual Infrastructure Node bundles our datacenter-class ESX Server product together with the revolutionary VMotion and Virtual SMP add-ons and a VirtualCenter Agent for advanced management.
It has always been easy to move GSX Server virtual machines to ESX Server hosts when you need the performance and robustness of its bare-metal architecture. This new upgrade program now lets you replace your GSX Server software with the VMware ESX Server Virtual Infrastructure Node bundle at a price that gives full credit for the list price of your GSX Server purchase.