I posted this issue at http://semeb.com/dpldemo, but Gero said he no longer maintains this extension. I hope this valuable resource is still being maintained, because we use it a lot on our wiki. Here is the issue I found, with the URLs fully qualified:
The example shown at http://semeb.com/dpldemo/index.php?title=Execandexit#execandexit no longer works. It appears that <code>geturlargs</code> is not setting the dplvars. I copied the example to my wiki here: http://forgottenrealms.wikia.com/wiki/User:Moviesign/TestDPL2?cat=Gems and I get the "please specify a category via &cat= in the URL!" message regardless of what I put in the URL. I discovered this when the template http://forgottenrealms.wikia.com/wiki/Template:Category_intersection Category intersection stopped working.