This is one of those funny cases where the etymological connection has been a bit obscured by time. Patents are called such because they are "open letters" disclosing the invention. Patent : Open :: Latent : Hidden.

Of course in this case it's patent that patent disclosures are not what is being referred to. :-)

Just saw your comment: Thanks for the insight! Now that I understood the root causes and laughed at the related word play, I won't forget anymore :)