A child process, which ends bevor the parent process calls a wait() will become a ZOMBIE. This means that all opened files will be closed and all used memory will be freed. The process occipies an entry in the process table until the parent process does a wait() call or the parent process ends itself.
If the parent process ends before the child process than the INIT process will "adopt" the child process and become new parent process.
This is from my (German) operating system lecture.
@duststar: You were right, but as I already said: "With more than a bottle of wine in my head I cannot say that I am sure about what a ZOMBIE exactly is."
Now everybody will think we are ZOMBIEs or at least freaks that have nothing better to do than talk about operating system while beeing drunken