If you ever doubted the importance of long tones then check out this lesson by Matt Otto.
Of particular interest to me was the fact that the practise of long tones are essential for helping to stay relaxed while playing. If you feel like me, that you sometimes find yourself overblowing or tense while playing, following the method outlined in this lesson helps to avoid this by developing better long term habits.
Once again, thanks goes to David Valdez's blog for finding this. This site is really the best jazz site I have seen on the web and essential reading for any serious musician.