In developing my future post on Layer Standards, I have noticed that in the 2009 release, any changes made to the Layer Standard, Layer Key Styles or Layer Key Overrides when accessed through the Layer Properties Manager (the ClassicLayer, modal dialog, not the non-modal palette version, which does not have access to the ACD-A layer features) will NOT be saved if these are the only changes being made during that session of the Layer Properties Manager. While less critical for Layer Key Styles and Layer Key Overrides, since these can be accessed outside of the Layer Properties Manager, this is quite serious for Layer Standard changes (imports from other files, creation of new Layer Standards or edits to existing Layer Standards), since the only way to do these is through the Layer Properties Manager.
Fortunately, there is a workaround for this: after completing your Layer Standard, Layer Key Style or Layer Key Override changes from the Layer Properties Manager, before selecting OK, do something directly within the Layer Properties Manager that will result in the Apply button becoming active. My personal favorite is to select the New Layer button, and simply add the default layer (Layer1 if it does not already exist). If you like, you can immediately delete this newly added layer, and then select the OK button.
From what I can tell, it appears that changes made to Layer Standards, Layer Key Styles and Layer Key Overrides from the Layer Properties Manager are being held in a "pending queue" without being applied to the drawing (in memory) when selecting OK in the dialog(s) launched from the Layer Properties Manager toolbar buttons. This would allow for possible remorse while the Layer Properties Manager is still active - I have no problem with those changes being discarded if I select the Cancel button in the Layer Properties Manager. Unfortunately, unlike previous versions, the 2009 Layer Properties Manager dialog starts out with the Apply button disabled, and not only does it not become enabled when a change is made to a Layer Standard, Layer Key Style or Layer Key Override through the Layer Properties Manager, these pending changes also do not appear to trigger the need for acceptance should the OK button be selected. Making a change in the Layer Properties Manager itself does activate the Apply button and also sets something that activates all pending changes when either the Apply or OK buttons are used.
While this should not be necessary, until it is fixed, creating and deleting a bogus layer is a relatively small act to preserve what could be many minutes (hours?) of editing a Layer Key Style or adding descriptions to a Layer Standard.