I've seen a few partition edits go wrong and fixed them (without loss of data) a couple of way, but I had still backed up all data first just in case, even though it turned out I didn't need the backup. That said, I've never seen gparted go that far wrong. I can only imagine that there was a power interruption while it was working.
I will make a few suggestions, each with a link, none of which are remotely guaranteed to work, though I'm confident that what some of them reveal may help us all to help solve this.
I would first recommend you boot your computer to any live boot CD and open the included disk utility. The odds are your hard drive will again appear unformatted with unallocated space, but it is always the first thing I do when things look weird. It's like I want a second opinion just in case one program is acting wonky. In general, gparted works great, but a lifetime of experience has taught me never to assume that any one person or program is correct.
The next thing I'd try is the near-miracle repair disk. It makes a bootable cd which you first boot your computer to and then use the utility within to analyze your hard drive's boot issues. It is primarily made to fix problems with the grub, but I've seen it perform unexpected miracles. It is possible that in searching for bootable partitions, it will recognize the messed up partition table and restore it. Personally I doubt it will help, but it probably won't hurt anything. When it offers you a url for further diagnostics, please record it and post it here in case any of us can decipher it.
I will now list the utility most likely to help you. It is called Test Disk. While I like that it claims to run under everything, I dislike that it appears to need a working operating system to work, which seems stupid. I would run it under one of my live booting usb flash drives, personally, but most people aren't using those. I personally think this product would benefit more people if they offered it as an ISO image download from which we could make a self-booting cd or flash drive in the same manner we currently employ the boot repair CD.