Re:
GCN did a video about it a while back:
[youtube]https://www.youtube.com/watch?v=FaKl3OymFy4[/youtube]
It's not as high tech as you might think, it isn't sheets of 1 molecule thick graphene, but a graphene powder that is used as a filller in the epoxy resin.
A 750g frame is still incredibly light though.