Windows 7 has eliminated the Windows Sidebar and instead has placed gadgets (widgets) directly onto the desktop. They've also gotten rid of the Notes gadget and replaced it with a program called Sticky Notes.
Getting rid of Windows Sidebar has actually made using the gadgets less cumbersome than it was to use in Vista. Previously in Vista, the Show Desktop function would minimize the Sidebar program, so you wouldn't be able to see your gadgets. In addition, memory dumps and program crashes in Sidebar prevented you from using your gadgets completely.
Accessing the gadgets in Window 7 may seem like a mystery at first, until you right-click the desktop. In the drop-down menu, you should see "Gadgets," or as an alternative, you can access them in the Control Panel. In the beta, eight default gadgets come installed: Calendar, Clock, CPU Meter, Currency, Feed Headlines, Media Center, Picture Puzzle, Slide Show, Stocks and Weather. There hasn't been any major overhaul to the gadgets that come preloaded with Windows 7 themselves-they are just as customizable and function exactly the same as if they were in Vista. Not surprisingly, I had no trouble installing any gadget made for Vista from Microsoft's collection online.
Notes gadget is not installed by default—I was surprised to find it missing, but instead I found a program called Sticky Notes that is apparently intended to replace it. Accessible from the Start Menu under Accessories, the Sticky Notes will actually resize to its contents unlike the Vista gadget. It's an overall improvement, but the notes lack the ability to customize your font and the ability to change the opacity. But it does bring Windows 7 up to OS X's Stickies in desktop-level sticky note functionality.
Even though the Windows 7 beta seems stable for the most part, there are a few quirks here and there and gadgets are no exception. The gadgets seem to be incompatible with certain User Account Control (UAC) settings. I didn't notice it until I turned my UAC settings completely off to do something and my gadgets disappeared. I turned them back on (and voila!) my gadgets came back. Seeing how UAC settings now seem to be directly involved with Administrator status (more to come on this), it's annoying to constantly reboot if you want your gadgets. Hopefully, Microsoft will fix this bug in the final release.
Update: There is a fix for the gadget/UAC bug. Also, Sticky Notes is apparently not a new feature, but a carryover from previous editions of Windows. That doesn't change the fact that the Notes gadget is still gone. Also, if you have a computer with any type of pen input, you can "ink" straight onto the notes as well (thanks Anthony!).