The first guide that includes 2012 R2 RTM versions of System Center and Windows Server is out. You can download it now and save it to be prepared to test certain scenarios when GA availability of R2 wave arrives.
Multi-Tenant Gateway Testing Guides
In Windows Server 2012 R2 Preview Microsoft is introducing Multi-Tenant Gateway. The GW is easier to setup with VMM 2012 R2 Preview but if you want just to test the GW in a small lab here are two guides that will help you in that:
Both guides are provided by Ramandeep Singh Dhillon from Microsoft.
Test Lab Guide: Windows Server 2012 R2 Hyper-V Network Virtualization with System Center 2012 R2 VMM
Even though SC 2012 R2 and WS 2012 R2 are not released yet Microsoft published a guide to setup lab for Hyper-V Network Virtualization. There are no screenshot in the guide but you can have a sneak peak preview of the architecture of the new Multi-Tenant NVGRE Gateway. Check it out here.
Simulate monitoring of network devices with Jalasoft by Kevin Holman
Very good article by Kevin Holman if you plan to test network devices monitoring in SCOM.
Hyper-V Replica and Riverbed document
This document captures the results from the bandwidth optimization experiments conducted in the Microsoft® Engineering Excellence Center (EEC) lab by using the Riverbed Steelhead appliance WAN optimization devices with Windows Server 2012 Hyper-V Replica.
So basically if you use Hyper-V replica across WAN you should use WAN optimizers in order to reduce traffic and bandwidth. You can see the results from the document here.