The wiki on readyboost seems a good place to start:
ReadyBoost - Wikipedia, the free encyclopedia
It seems that readyboost can indeed speed up access times, but as noted in the wiki, it is best at
random access requests. So for stuff like streaming video, a regular hard drive (IDE/SATA/PATA) would be just as fast, and in the case of a flash drive hooked through USB, the regular hard drive would perform much better because of limitations of USB and flash access times for sequential access. For games, I suppose it would depend a lot upon the particular game.
