Our iSCSI Boot guide is now available. This provides information on iSCSI boot, as well as stepping through the process of creating and deploying iSCSI boot images:
http://technet.microsoft.com/en-us/library/ee619733(WS.10).aspx
Just for info: A new and little known feature of the HPC (High Performance Computing) 2008R2 product is the ability to easily setup up and deploy iscsi boot compute nodes.
channel9.msdn.com/.../Windows-HPCS-2008R2-Beta1-Deploying-Diskless-Compute-Notes