Tip: Quick way to change taskbar tray icon visibility
Windows 7 has kept the taskbar tray from previous versions of Windows, but is providing a different means of managing which icons always show up and when (e.g. can set a specific icon to show up only if they have notifications, or even to never show up on the tray). When you press the “up” arrow UI button that is just before the taskbar tray you see a popup with the hidden icons and pressing “Customize…” you see a dialog where you can set per icon options or select to “Always show all icons and notifications on the taskbar”.
A quick (and quite useful on both tablets and classic desktops/notebooks) trick though is that you don’t need to show that Customize dialog, you can just show the small popup with the hidden icons and drag an icon from there to the taskbar tray to make it always show up. The inverse is also true, you can drag an icon from the tray to that popup to make an icon show up only when it has notifications.
Note that if the Customize dialog is already open its UI gets updated with your changes on the fly, but you then have to press OK to keep the changes, pressing Cancel will undo even the changes you did via drag-drop.