Is RAII sufficient for memory management?
mbrubeck: RAII doesn't provide an obvious, simple way to release memory in the presence of cyclic references.  You may be able to use weak references to fix this, but that requires the programmer to notice the problem and explicitly specify the solution.  Automatic GC takes the burden off the programmer in this case.  (On the other hand, RAII provides for greater control, and works for resources other than memory too.  Both techniques are useful tools.)