If you are creating a sidebar gadget that displays photos, you need to accommodate for both landscape and portrait and not force your user to choose one or the other. Google shockingly has done a horrible job of this.
I took some pictures of my beautiful wife over the weekend, and threw them onto my computer. I use Google desktop, so I thought I'd try out their photos gadget to see rotating pictures of her while I work. I ended up very frustrated.
Google's sidebar gadget allows you to choose between portrait,landscape or re-sizeable. If you choose portrait or landscape, it automatically formats it perfectly for one or the other. If you choose re-sizable it allows you to expand or contract it to fit either. But there is no setting to make the picture automatically fit the current size (by throwing black bars around the picture or something). This is absurd. It means that all of the landscape pictures I took get clipped off at the edges if I am on portrait mode, or all the portrait pictures get clipped off if I am on landscape mode.
Windows Vista's sidebar did add in the black bars, but unbelievably gave you no option to resize! This meant that if you were viewing a portrait picture you could pretty much forget actually getting to see anything in the picture beyond just a vague idea of what it is. Even the landscape pictures were poorly scaled down causing people to look rather funny/goblin-esque/gimpy-eyed at times.
Google's gadget allows you to add as many local folders, and even websites, to harvest pictures from as you want, Windows' only allowed you to choose one folder, but did at least allow you to specify that you would like to include all sub-folders as well.
All in all I was very disappointed about my options for a miniature photo slide-show on my desktop. If anyone knows of any better options, please let me know.