Google Dance
It is true you will sometimes see listings on Google which seem to incorporate DMOZ results but this is because the robot that google uses is not just restricted to the web site it visits but also seeks links to the web site (This is the main context of rankings). Being that DMOZ is probably the most influential directory of 'Links' on the web it draws from it possibly giving it more credence than links elsewhere.
The same as a search on Google may show because the item, issue or company are featured on another site and the context of search means that Google finds the keywords you have input whitin those listings rather than draw from the hosted site itself.
A good example may be a product you are seeking. You may find on a search this displays online reatialers selling this product rather than manufacturers web sites.
The main ranking system has been changed on Google and has changed twice recently this has been dubbed the 'google dance' as previously stated Yahoo and MSN are using their own robots and pay per click to acheive their own results.
http://www.webpronews.com/ will fill you in on developments in this feild and give you an idea of Search engline wars.
The most inportant aspect of ranking on Google is how well you site links to others and vice versa a piece of free software called link popularity check will assist with this.
The long and the short of it is DMOZ is a special animal and most of the general public are fickle unless they know of dmoz then they are unlikely to visit.
They want results even if they are not always as pertinent as the data they could find in DMOZ.