Came across a requirement where we needed to hide the "Upload Multiple" toolbar menu item from the default view of document libraries.
Observed that using the "HideCustomAction" section in a custom feature file doesn't work for this.
Workaround - Edit the DefaultTemplate.ascx file which renders the menu
<SharePoint:MenuItemTemplate ID="MultipleUpload" Text="<%$Resources:wss,ToolBarMenuItemMuliUpload%>" Description="<%$Resources:wss,ToolBarMenuItemMuliUploadDescription%>" Sequence="200" ImageUrl="/_layouts/images/MenuUploadMultiple.gif" HiddenScript="!browseris.ie55up" UseShortId="true" runat="server"/>