In general anything that uses Cr2 (Figures), Pp2 (Props), Pz2 (Poses), Hr2 (Hair), Fc2 (Face Expression Poses), or Hd2 (Hand Poses) formats will work in Daz or Poser both without difficulty, though as said by others some tweaking of surfaces may be needed to get the right effect for rendering.

Then again, most users will tweak surfaces settings to get various effects of lighting and look in Daz or Poser anyways, no figure is every completely perfect out of the box so to speak...

The exceptions are weight-mapped figures which as stated above are handled differently in Daz than in Poser, and Dynamic clothes/items which are also handled differently between these two programs. Poser "proceedural" textures/materials won't function in Daz (noted above as well I beleive) either...

Also light sets won't transfer between Daz and Poser, nor will camera presets...

Aside from those how-ever, pretty much any Poser file will work in Daz as well (I may have missed a few file types and if so I apologize), and most will require little or no tweaking to work except for touching up surface/material settings...

 Looking over a product readme file should give you an idea if proceedurals have been used for materials or if weight-mapping is present, as should most product descriptions...

I regularily go back and forth between Daz and Poser when I create items and haven't had any major issues with standard files between the two (actualy I've been able to figure out what base surface settings will transport from Poser to Daz as almost identical values). I use Daz's figure set-up tools to create products that function in both Daz and Poser with out too much issue at all...

I hope this helps some... :)