The starting point for any developer is http://www.vmware.com/developer but as there is a overwhelming amount of information available, we are trying to make it easier accessible on this site.
Hopefully we'll succeed at that over time, it is a pretty high goal. It certainly isn't the case yet, but time will tell.
Management Virtual Machines
VMware ESX 3.5 and earlier had the management Service Console, a stripped down RHEL console which was could be used for automating and managing your virtual machines. As of ESXi 3.5 this is no longer available and the future is to move away from this "fat hypervisor". In order to manage your virtual machines in a similar way as before, we now have special virtual machine that come with management software pre-installed. VMware delivers this as a virtual appliances called VMware VIMA containing RCLI (Remote CLI) and VMware VI Perl Toolkit to aide in managing your VI infrastructure.