I think I have the GR-DVP9 but I can't remember (it's in the shop right now, and never buying JVC again). Anyway if I'm right you have the MultiMediaCard for taking still pictures. First let me say I haven't actually used my PB to look at still pictures taken from the camera. That being said, I think that if you get a seperate USB MMC reader you will have no problems whatsover (that is as long as the MMC reader is supported by OSX).
The card itself is just saving .jpg files so as long as you have a reader it should be no problem to get the files off it. Because the camera is a bit older OSX doesn't know how to reach these files through the camera. Generally, I think readers are only around 20-30 bucks so it's not a huge expense and I used to have one for my PC and was actually much more convenient then having to hook the camera up every time.
Hope this helps.