Take a look and the Software & Operating Systems forum (tag), inside you will see Apple, Mozilla, Microsoft, Security, and Software. Is this a good way to start organizing the community? A side effect of this is that the primary forum, Software & Operating Systems contains all discussions of the subforms (tags).
Also take a look at the form list on the homepage. I am thinking to place the ISP forums after general purpose forums. I am thinking that users will hunt for the ISP they want to discuss. This makes it easier to discover the other forums.
If we decide to enable it, a single discussion can be referenced in multiple tags (forums).
What do you think?