It's hard to say, because it's quite rare to find a site that is linked through Dmoz alone. You also have to add into the equation the effect of the many Dmoz clones, which individually may have very low PR but together might give a site quite a boost. These clones update far less frequently (and sometimes never), so you'd have to factor that in.
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.
I've seen a website on DMOZ of a PR of 4. The amazing thing(not in a good way) about this site is that it is only one page with no links to other sites and the only content in it was that this site is for sale. I sent him an email to see how much he wants, if he askes too much im going to report him.