One of the biggest limit (or benefit, depending on point of views) of VMware ESX Server is its limited support for hardware and software.
For example customers cannot try the product on cheap IDE/SATA lab implementations, cannot replace embedded iSCSI initiator (currently a very old Cisco implementation), etc.
Company policy about HW/SW support is now slightly changing, with the publishing of a community driven Hardware/Software Compatibility List: VMware customers inclined to experimentation can now report which products are working with which version of ESX Server, while other can provide a rating on suggested implementation.
VMware support will act accordingly:
VMware Global Support Services (GSS) will assist customers in problem analysis to determine whether or not the technical issue is related to the 3rd party hardware or software. In order to isolate the Error, we reserve the right to request that the 3rd party hardware or software be removed. This will only be done where we have reason to believe the issue is related to the 3rd party hardware or software.
If VMware GSS cannot directly identify the root cause or it is reasonably suspected that the problem is related to the 3rd party hardware or software, we will direct the customer to open a support request with the 3rd party vendor’s support organization.
It’s reasonable to think VMware will use this initiative to lower testing costs, understanding which 3rd party products are more requested, and using community efforts to recognize which integrations are more reliable, so to move them, after enough QA, to the official ESX Server compatibility guides.