stateless bean need not be passivated. Because of the fact that they are stateless, they can be pooled in to service multiple clients (remember MTS components?) How stateless bean can be pooled to service to multiple clients ? Does it use same concept that Entity bean does normally?
Stateless session bean do not store any state. When a client invokes a method on stateless session bean , a bean from the pool is chosen to process the client request. After the method exits the bean is pu back into the pool. It can go into the pool because it does not store the client state i.e it does not remember who the previous client is. The bean can be used to serve future client requests.