When I take photos, I like to place a flash behind the model's head and aim it at the hair, giving a hair light halo effect by highlighting the hair edges.

Is this possible in poser? I tried aiming a spotlight at the hair from behind the figure, but didn't see any lighting change.

This is what I mean:

You can see the rear light on her shoulders, but it doesn't seem to affect the hair at all.

smells like one of those poser issues. personally, i never had this problem. but if i had this problem, i'd try flipping the hair's normals ... just to see what happens... i hope someone else has more advice to offer...;)

Are there any example specular values I should use for hair? I'm not exactly sure of its properties.

BTW I'm using raytracing with the lights,instead of shadow mapping. Is this alright?

Would love to, but the style I want doesn't come in dynamic hair.

I'm quite new to the material room, so does this material setting look like it should?

http://www.flickr.com/photo_zoom.gne?id=2196594095&size=o

Ok, I've flipped the normals and added the blinn specular highlights, but I still think it doesn't look right. Is there any way to get the glow that you see at the back of the right shoulder, around the hair? The light is already in place, so I don't understand why if doesn't reflect slightly off the hair.

BTW I noticed the shadows are quite rough. This wwas reendered on the highest setting and the shadows have jagged edges. Is this normal?

Jagged shadows are most likely due to an incorrect setting of Shadow Min Bias, on the light's parameter setting, Properties tab.  Set them to something between 0.25 - 0.28.

Try plugging the Blinn shader into Alternate _Specular on its own, without using a Blender or anything else attached to it.  You should get harder, more metallic highlights, which is generally the hallmark of really glossy hair.

You may not have the specular nodes set up quite right, or they need to be tweaked for this hair.

The purpose of the blend node between the blinn shader and the alternate_specular input on my example is to apply the transparency map to the blinn shader, Stewer is doing the same thing by plugging his Image_Map_3 into the Anisotropic shader's Specular_Value node.  You may certainly bypass it for a test render as SamTherapy says. 

Try setting the blinn node Specular_Color to white.  Also increase the SpecularRollOff and Eccentricity towards 1.