As Ockham says it is highly dependent on both how you export from Poser, using the option he shows being the key point, and how good the OBJ importer is in your modeler - not familiar with Blender so I've no idea there, but I can tell you for sure that it varies greatly from modeler to modeler.  Cinema 4D's builtin OBJ importer for example can't handle material zones and/or polygon groups.  Some other extremely important tidbits:

• TURN IK OFF BEFORE EXPORTING!  This should be the very first thing you do before exporting anything.  Make sure that Inverse Kinematics is off for the figure, because in many cases (all character figures I can think of) the figure is not at zero pose when loaded, and if you do not turn off IK, when you do zero the pose, the figure still will be deformed away from the default state.
• ZERO THE FIGURE BEFORE EXPORTING!  Bones apply a deformation to the mesh of the figure when not at zero pose, and this will be exported if you don't zero the figure first.
• DO NOT SCALE ANY BODYPARTS BEFORE EXPORTING!  Again this applies a deformation to the mesh, and it will be included with the export, which is bad.  In some figures, e.g. V4, dials that appear to be morphs actually adjust scale.  Be certain to make these dials zero before exporting; you can set them to whatever they need to be at the last step.  The tricky part here can be figuring out what dials are actually of this type. 

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