For a consulting project, I recently had to join my laptop to an Active Directory domain at a client's workplace.  Suddenly, my home computers can no longer see the computer.  I found that the laptop could see shared items on my home network, though.

I went to the "Network and Sharing Center" to see if there was some setting I had to tweak and found this:

Hmmm... so I'm kinda/sorta still part of a homegroup, it sounds like.  Searching for the message highlighted I found this Windows Online help topic that explains it:

http://windows.microsoft.com/en-US/windows7/Switching-between-your-home-and-workplace-networks

So it turns out that yes, you can see other computers from the domain-joined laptop, but the other computers on the homegroup can't see the domain-joined laptop any longer.  I suspect this is a security thing.