Logout with shadow icon is included into Basic Vista Icons. You can view all icons here:[link]
Each basic vista icon is available in sizes of 16x16, 24x24, 32x32, 48x48 and 256x256 pixels. All images are supplied in ICO, PNG, GIF, and BMP formats. Your order will get you all icons in have 256 colors and True Color variants. These adorable icons come in two versions: casting a shadow or without it.
Download link: [link]