First post for me, but I actually deal with some of this stuff in my job so I thought I'd chime in.
What we actually know is that Armada sent Rossignol (and some others) a letter informing them that they are selling a ski that uses invention or inventions documented in a patent that Armada had previously been granted.
A patent doesn't stop someone other than the holder from using an invention, it means that the holder can ask for some form of compensation for the use of an invention - this is probably what Armada is talking about when they are discussing funding a charity with the proceeds. It's likely not proceeds from a lawsuit, but instead, proceeds from royalties obtained from others using the invention documented in the patent.
Indeed, those letters will be in the form of a legal threat. Rossignol launching a suit in retaliation is fairly common practice in all industries - companies spend a lot of money building portfolios of patents as a defense against exactly this sort of thing.
With regards to the patent itself, a shape of ski that is novel can indeed be patented if it isn't obvious to one well-versed in the art of ski-design. However, it remains to be seen if that is the case here. One of the issues with patents in general, and the USPTO in particular is that the volume of patent applications means that the USPTO fails to investigate in depth whether or not an invention truly is novel and new; therefore the true test of a patent's value is a test in court. Frequently what will happen now is that the lawyers will get together, bill ridiculous amounts of money to their respective clients (but smaller amounts of money than they would if it actually went to court), and the world will go back to normal, with the costs passed down to the customer.
FWIW, I dislike the idea of patents in general. Engineers often feel that patents are sensible in fields other than their own - and from looking at all the evidence I've come to the conclusion that patents in general have outlived their usefulness.
Due to the of the huge number of patents in every field a move like the one Armada is making is dangerous due to the defensive patent portfolios built up by the company you're looking for royalties from (often you're using somebody else's patented invention, even if you don't realize it).
It's a cold war, turned hot, and it's unpleasant to see.
