Wormhole Attack is not realistic attack !!!!
Very recently, I started working on security in wireless network. Due to my background in intrusion detection, I started doing a survey on attacks in wireless network. I have come to know about many attacks, and wormhole attack is one of them. To know in detail about the attack, just do a google search and you will get many pages. Very briefly, this is an attack that is launched by two adversaries to gain control over a communication between two nodes. Lets say there are two nodes A and B that want to communicate each other. There are two adversaries X and Y s.t. X is near to A and Y is near to B. X and Y have out-of-band channel to communicate with each other. Whenever, A sends a route request, X gets it and relays it to Y, which in turn, forwards it to B. So B thinks that A is only 2 hopes away from it and A and B chooses this path i.e. A -> X......Y -> B (please note that i have made the picture very simple, please read more). Following figure makes it simple to understand (i have stolen the figure from Internet!!).

If you observe carefully, U will find that Y should ALWAYS be in vicinity of B. Given the mobile nature of wireless ad-hoc network, it is very careless assumption. How can one be sure that given a time, B will be at a particular place and Y will be there also to have this attack successful? I feel that security designer of wireless network should not worry about wormhole attack. In practice, we'll not see it very often, if not at all.