Checking for empty queryset in Django

What is the recommended idiom for checking whether a query returned any results?
Example:

orgs = Organisation.objects.filter(name__iexact = 'Fjuk inc')
# If any results
    # Do this with the results without querying again.
# Else, do something else...

I suppose there are several different ways of checking this, but I'd like to know how an experienced Django user would do it. Most examples in the docs just ignore the case where nothing was found...

if not orgs:
    # Do this...
else:
    # Do that...

Since version 1.2, Django has QuerySet.exists() method which is the most efficient:

if orgs.exists():
    # Do this...
else:
    # Do that...

But if you are going to evaluate QuerySet anyway it's better to use:

if orgs:
   ...

For more information read QuerySet.exists() documentation.