Forefront Client Security - license per user and workers can install the non-managed client at home for free

Pretty cool if you ask me. Sort of like the Home Use license, but better.

To quote the post here:
Customers who license the Client Security agent on a per-user basis can provide the Client Security agent to employees at no additional cost for protecting home computers. These home-based Client Security agents must be deployed in an unmanaged configuration; they will not be able to report to your Client Security servers in your enterprise.

Installing the client without the management portion is very easy - as simple as clientsetup.exe /nomom.