[v64]

I don't know how valid it is now, but in July of 2011 I reverse engineered some aspects of Zynga's Words with Friends and put it up online: https://github.com/v64/fiend

The most interesting part was the way they decided to do the random generation of letter tiles. At the start of the game, each client was given the same PRNG seed (in the case of Words with Friends, the PRNG was a Mersenne twister), and when tiles needed to be drawn from the bag, instead of having the server tell you what tiles you received, you would use the preseeded PRNG to randomly draw your tiles from the available pool.

Of course, as your opponent is also doing this with the same preseeded PRNG, this also allows you to determine what tiles your opponent has, and what order the tiles will be drawn in for the rest of the game.