On-Disk’s solution is called Xtra Ordinary. For $41.09 you get a 4GB SD card with a Debian Linux-based operating system that uses the LXDE desktop environment. It feels more like a typical desktop operating system than Sugar OS, and uses a layout with desktop shortcuts, and a Windows-like taskbar and start menu.
As you already know, I think quite highly of Sugar, and especially its innovative UI.
I suppose this solution could turn an OLPC into the world's cheapest ruggedized notebook -- then again, who would bring an OLPC to somewhere like a construction site and expect to be taken seriously?