If you log into the Test server you can see an early implementation of shadow maps for EQII. I'm really excited about this feature going in and its something we've been wanting for awhile. Ryan Favale has done an excellent job adding this new shadow system to EQII. Now you'll have a choice between shadow volumes (CPU) and shadow maps (GPU). There will certainly be situations depending on your computer hardware and the zone you're in where one might be faster than the other and vise versa. But this option will at least let you choose the shadow system that works best overall for your system.
There are some inherent differences between the two shadow technologies and if you're interested to read more about how they work, there is some decent information on Wikipedia. We are using something similar to the cascaded shadow map system described below.
Shadow Maps (GPU)
Shadow Volumes (CPU)
If you get a chance to try these out on the Test Server, please give us your feedback in the following thread. Ryan is still tweaking for performance and quality as well as fixing bugs as he's made aware of them. So the more feedback we get, the better!