The letter itself isn't too illuminating; Hofmann was an incredible 101 years old at the time of writing, and merely mentions that he knew Jobs had mentioned LSD in a positive light in the press. Hofmann asks whether Jobs would like to contribute to an LSD-assisted psychotherapy study, and colorfully asks for Jobs's assistance in turning his "problem child" (Hofmann's pet name for LSD) into a "wonder child."
But the story around the letter, and Jobs's affiliation with the hallucinogen, are pretty interesting. Check out the original text (Hofmann's got great handwriting for a guy 101 years old) and background over at HuffPo, and read our exhaustive summary of the life of Steve Jobs here. [Huffington Post, thanks Caitlin!]