For CS5, Windows 7, ActionScript:
I very innocently assumed that I could use myDocument.select(myLayer) to select a Layer. However this explodes at runtime with a parameter exception saying that the function select() expected to recieve either an object or an array of objects, but instead recieved a Layer. Is a Layer not an object? Is this a known limitation?
select() only works on actual objects that you can select in the UI as well. A layer is *not* an object you can select that way -- you can't "select a layer and delete, copy, move, etc." as you *can* with objects that are your page.
Think of it like the menus; surely you can "select" a menu item with the mouse? Layers are like pages, swatches, and paragraph styles. There is a correct way, though, to make the layer you want selected: activeLayer (see "Element of" in the Layer ref.: http://jongware.mit.edu/idcsjs5.5/pc_Layer.html).