A friend of mine passed along an interesting problem regarding DataGrids. They had the need to hide certain columns and then dynamically load the data. When doing this as expected, such as dataGridName.dataProvider = yourArrayName, the hidden columns would not stay hidden. The workaround to this issue is to track the visibility of each DataGridColumn, set the column to visible, and then override it with the visibility status we stored.
View the example here and download the code here.
Definately not optimal, but it works... ;-)