I saw that! 53.6 mph!
The sails are only a slightly different than the ones we can buy. A few pictures ("joining 45 knot club") look like they are using stock Naish sails. Maybe a little more than usual pretwist?
The booms are very different. They have a compression member and half wishbone on the windward side and nothing to leeward. I suspect their fins may be asymmetrical as well.
Earlier this year there was a record attempt at Fuertaventura. I think they Bjorn Dunkerbeck hit 44 knots on the ocean using slightly less exotic gear.
Check Video 3 here. The water looks hard.
http://www.hgs.at/wss/news/details.aspx?id=17#I hope they post some video on masters of speed too.
-colin