Back a few months ago I shared about the joint reference architecture that was able to boot and login 5000 users in 30 minutes. Using the Cisco UCS running VMware vSphere, with Citrix XenDesktop and an EMC VNX 7500. Cisco and Citrix answer a few questions with Craig Chapman on the joint validated design in this video:
I really like this layout and it usually takes pretty pictures to get me interested. Here is a high level overview of the design.