It already does.
You can get the RSAT tools from here
They include the Hyper-V manager for Windows 7.
After installing the above download, go to Windows Features in Control Panel and choose the 'Role Administration Tools'. Select Hyper-V Tools from there.
I would say it isn't possible to use Hyper-V on Windows 7. You could put Server 2008 with Hyper-V as the host and use Windows 7 as a guest machine. Your best bet is to either use the new Windows Virtual PC or VirtualBox and the like.
All server management tools that are part of the Remote Server Administration Toolkit (RSAT) for Windows Vista manage only Server 2008. And all server management tools that come with Windows 7 (as RSAT) manage only servers running Server 2008 R2. And all server management tools that are part of Windows 8 (in this case, built in -- not the RSAT) manage only Windows 8.
This is true for all server rolls, not just Hyper-V. And you wouldn't be the first person to say that you wished for something different.
If you want something that manages different types of servers from the same console, and you want it to come from Microsoft, that's System Center Virtual Machine Manager.
Best Answer
It already does. You can get the RSAT tools from here
They include the Hyper-V manager for Windows 7.
After installing the above download, go to Windows Features in Control Panel and choose the 'Role Administration Tools'. Select Hyper-V Tools from there.
Edit: Link updated to current version.