What did Australian author Harry Nicolaides write which so offended the Thai government and caused them to jail him for lese majeste? Thanks to the Streisand effect, the relevant excerpt is now available on WikiLeaks:

From King Rama to the Crown Prince, the nobility was renowned for their romantic entanglements and intrigues. The Crown Prince had many wives "major and minor" with a coterie of concubines for entertainment. One of his recent wives was exiled with her entire family, including a son they conceived together, for an undisclosed indiscretion. He subsequently remarried with another woman and fathered another child. It was rumored that if the prince fell in love with one of his minor wives and she betrayed him, she and her family would disappear with their name, familial lineage and all vestiges of their existence expunged forever.

(The entire novel is also available here [PDF]. Given that it only sold seven copies, I don't think anyone is going to be losing money over it...)

So, basically establishing that the (fictional) Crown Prince has absolute power and uses it in his self-interest. You can see how the Thai government (who through the monarch have absolute power and use it in their self-interest) might be upset by that - but the fact remains that in a democratic society, nothing is held sacred, and you are allowed to say these sorts of things.

Unfortunately, as we've seen in recent years, and in recent use of the lese majeste law, Thailand isn't really a democratic society...