I can\'t seem to find the prope
Found the answer here: http://social.msdn.microsoft.com/Forums/en-US/MSWinWebChart/thread/32ccd993-5f43-47a3-bcbc-e772a13a87fe
It turns out there is an obscure DataPointCustomProperty called PieLabelStyle that governs label visibility in pie charts. Worse still, the property must be set on each data point.
for (var i = 0; i < chart.Series.Count; i++)
for (var j = 0; j < chart.Series[i].Points.Count; j++)
chart.Series[i].Points[j]["PieLabelStyle"] = "Disabled";