According to the HDMI 1.4a spec, one of the "secondary" formats is 1920 x 1080 at 60 Hz, with a "Frame-Pack" encoding. This means two full 1080p frames, both at 60 Hz. So if the source (GPU) and sink (HDTV) both support that format, then a aystem should be able to use it.
Don W claims that HDMI supports only up to 24 Hz at Full 1080p, but that is an oversimplification. That said, I'd sure like to have a few words with whoever on the HDMI group decided that such a format shouldn't be given more importance. Implementation of any secondary format by source or sink is optional. I'm guessing that the primary formats (which include 1080p24 Frame-Pack, among others) were chosen because they all fit within the slower speed-caps of older HDMI cables. HDMI should have required that all 1.4a-compliant sources be able to generate 1080p60 Frame Pack, but they didn't. Thank you HDMI.