title: What's the shortest code to cause a stack overflow?
body: <p>To commemorate the public launch of Stack Overflow, what's the shortest code to cause a stack overflow? Any language welcome.</p>
  
  <p>ETA: Just to be clear on this question, seeing as I'm an occasional Scheme user: tail-call "recursion" is really iteration, and any solution which can be converted to an iterative solution relatively trivially by a decent compiler won't be counted. :-P</p>
  
  <p>ETA2: I've now selected a “best answer”; see <a href="https://stackoverflow.com/questions/62188/stack-overflow-code-golf/71833#71833">this post</a> for rationale. Thanks to everyone who contributed! :-)</p>