That is a question that only you can answer! How important is having GPS info in the Exif data worth to you? Adding GPS capability to existing camera bodies requires upgrading the hardware (adding a GPS unit) and not just a firmware upgrade. While it may be incorporated into future bodies the only way to add GPS capability to the current bodies is to add a GPS unit and a cord. Good Luck and Enjoy your Nikons!
I agree. Adding GPS function to existing camera bodies is not an easy work but should be quite complicated by add in a GPS unit and supporting software, and others. So it’s better to connect to GPS body to fulfill the geotag function. I plug Easytagger GPS on my D5000. It is small, easy to carry. It records not only geo info currently and rapidly, but also the route that I walked. It is worthy, I believe.
I use an external GPS (Garmin eTrex Hcx) not connected to my camera. I just make sure the times on the GPS and the camera are the same and then use a 3rd party program to match the image date and time to the proper place on the GPS track. I use Geosetter on the PC and Photolinker on the Mac, but there are a number of other programs and plugins that will do the same thing.
I like this setup because I don't want anything else hanging off my camera, and I usually carry a GPS when hiking anyway.
"GPS worth getting" - strictly your decision, "will Nikon add it to the firmware" - no, it requires hardware (with apologies to Marty, who has already correctly said this).
Now, if you need GPS data, you can add it to your image's Exif file with Nikon ViewNX 2. It's a bit of a pain until you get used to the procedure, but I think It's a pretty slick application of technology. Basically, ViewNX accesses a Google map where you place a pointer at the spot where you took the photo of interest. Latitude/Longitude data is returned and recorded in the Exif file.
I rarely need this info (certainly not enough to justify the cost and hassle of a GPS attachment to the camera), but I recently entered a contest that required the Lat/Long coordinates in the Exif file. ViewNX 2 to the rescue! Very nice! Kudos to Nikon.