Is there any way to create a virtual interface of sorts between two VDCs on a single Nexus 7000 switch? I've read that a physical cable is required (which is lame) however I wasn't sure if this was a feature that was added in a newer NX-OS release. I'm currently running NX-OS v6.2(14).
There is no way to do what you want to do. VDCs virtualize control plane and data plane in protected memory so that each is an independent virtual device, just like independent physical devices. You can, of course, ask Cisco to consider adding this feature in a future NX-OS release.
Communication Between VDCs
The Cisco NX-OS software does not support direct communication between VDCs on a single physical device. You must make a physical connection from a port allocated to one VDC to a port allocated to the other VDC to allow the VDCs to communicate.