Here is Windows 7 Pro x64 DVD being used to install Windows 7 Professional as a Hyper-V guest:
Note the absence of the version picker we had with Windows Vista.
We have other versions of the OS DVD being downloaded, but it is looking like we are indeed in a situation where there is a DVD/ISO for each version of the Windows 7 OS.
Microsoft Small Business Specialists
Co-Author: SBS 2008 Blueprint Book