I had some trouble getting an SPDataSource to work with DevExpress's ASPxTreeList. It was not showing any useful fields from the data source like the web title (I was getting a list of webs). Instead it had a column for some of the properties of the SPDataSource it self - so weird!
So, I set ASPxTreeList.AutoGenerateColumns = false, created my own TreeListDataColumn for the __spTitle field, and added the column to the tree list's Columns.
// get the list of webs
SPDataSource spds = new SPDataSource();
spds.DataSourceMode = SPDataSourceMode.Webs;
treeList = new ASPxTreeList();
treeList.DataSource = spds;
treeList.KeyFieldName = "__spID";
treeList.ParentFieldName = "__spParentWebId";
treeList.AutoGenerateColumns = false; // because it generates the wrong ones
TreeListDataColumn colTitle = new TreeListDataColumn("__spTitle", "Name");
Now it correctly lists the name of each web, like I wanted.