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More often than not, sites that get linked by Dmoz are picked up elsewhere before a PR update comes round. This could either be by other webmasters using Dmoz as a source, or by scrapers.
It all depends on the category, how crowded it is and the PR of the individual page, so YMMV. Very few will be boosted from zero to over PR5.
You are looking at about 2000 backlinks per link in DMOZ once all the clones have kicked in. The level of PR depends on how deep down you are listed in the directory
It can take a short while for the full effect as each clone updates and scrapers copy the listings.
So best try for two or three listings to max your backlinks. The more duplicated links you can get from DMOZ the better.