sufism and intercession (tradition, attend)

[aspergers_anomalous]

I find sufism fascinating and have attended zikr before. I was wondering, what are the traditional sufi defences for intercession from masters. A very controversial issue, of course... i would be interested to hear how you would understand this issue. How do you defend the Sufis from the charge of Shirk.

[Pariah]

There aren't too many Sufi's on this board, so you may have to research it for yourself.
I tried Google and Wikipedia with no luck.