I was the author of a Windows competitor named Kapsules back when Konfabulator was hot and before the buyout by death knell by Yahoo!. (I tried to go with Winfabulator but they didn't take too kindly to that - I was young and ignorant.)
This was a space that was useful, and then became saturated and commercialized to the detriment of usefulness. It was just before we had good off-screen rendering, right as the html-and-js-as-desktop-apps was starting to take off, and when transparency in window rendering was still difficult. I could share a lot more thoughts
Is there an opportunity to fill the void? I'm really not sure. Bear in mind that this was well before the iPhone hit and smartphone apps got huge. Most of the things we did with widgets back then are far easier done on our phones now. Kapsules had some good parity with what Konfabulator and Apple Widgets had offered, and I can't name a single widget for Kapsules, aside from the silly barking hamster, that doesn't ship by default with our phones now.
The widget craze was a fun phase of app development, and no doubt influenced UX and mobile apps, but I consider it merely an interesting footnote now. If anyone is interested in the source code for Kapsules, I can probably dig it up from one of my old HDDs. It was written in C# on .NET 4.0.