Open source. Why does uploading photos suck? Well, it takes forever, and when it doesn't, you have to download and install yet another browser upload control. So Jeff studied libjpeg, as well as a handful of other JPEG libraries, and built the first Silverlight JPEG library in C#, FJCore. It supports a wide array of JPEG formats, so it should "just work" for anybody using it to accelerate JPEG uploads. EstateSales.net uses this library and a custom uploader (see video).