Based on the discussion at:
http://groups.google.co.uk/group/comp.lang.python/browse_thread/thread/c1ae3513a31eb63e/d0701a9902732c67?hl=en#d0701a9902732c67

In the documentation of itertools, one of the functions provided in the recipes section (10.7.3) is consume:

def consume(iterator, n):
    "Advance the iterator n-steps ahead. If n is none, consume entirely."
    collections.deque(islice(iterator, n), maxlen=0)

A clearer implementation is:

def consume(n, items):
    if n == 0:
        return
    next(islice(items, n-1, None), None)

It uses no fancy tricks and is thus more suitable for a documentation. Moreover, the second implementation is actually more efficient. Some timings are provided in the thread linked above. As an example, here are the timings on my machine (Python 2.6.1, x86_64, OS X 10.6:

consume_deque #old implementation
    10: 1.2913839817
   100: 3.18093585968
  1000: 21.6316840649

consume_forloop #using a straight for loop
    10: 0.658184051514
   100: 2.85271406174
  1000: 24.6730420589

consume_islice #the suggested implementation
    10: 0.688861131668
   100: 1.15058612823
  1000: 5.52356886864

The script computing these timings is attached. Thanks to Peter Otten for coming up both with the function and the timing script.

As noted on comp.lang.python the implementation can be simplified to

def consume(items, n):
    next(islice(items, n, n), None)

When I suggested the above I wasn't aware that 

consume(items, None)

should exhaust the entire iterator. Unfortunately I've not found an elegant way to add that functionality.

Will switch to the version using next() instead of deque().

See r77721

Excellent solution and comments. Many thanks.

(sorry! typed into a wrong field)

Changeset r77721 should be ported to trunk, and py3k probably.

Remain calm.  I left the status as Open for a reason.  When I'm satisfied that people are reacting well to the new update, will port to other versions.

Mea culpa. Not knowing the conventions here, I closed the ticket, which probably resulted in florent's feedback. I will leave you to it then.

No problem.
Will forward port when I get a chance.

Raymond, before porting you should check the typos reported in issue #7778.