AlphaWolf - actually anyone can do exactly the same thing those guys are doing - an example:
If I take a domain that has something to do with pornstars and I build the main site from the root - I can get that listed in DMOZ.
Now I take a directory and put up a little subsite about Jenna J and add two galleries of 10 pics - and then get that listed in the image galleries section of DMOZ - and can do that hundreds of times with different pornstars
Of course all the while every one of those little subsites has a link back to the main site and the main site has a good sitemap or contents page that lists each of those subsites - an easy way to naturally move page rank around and a good surf for the users
And DMOZ will list each of those subsites usually - I only say usually as sometimes you will run into someone else that has that picture set already on DMOZ
As far as the large sites like msn etc. - Im not sure if building a portal and submitting subpages on varying subjects would fly - but it sure seems to
I dont think DMOZ would have a leg to stand on if they declined your subtopics and not the msns
Very important to remember - their policies dont say anything against submitting multiple sites from the same domain