Specifying that Ivan Krstić is in no way a disinterested observer at this point, here's a new quote from him:
Right before leaving OLPC, I was tasked with re-architecting the tremendous mess that is the OLPC datastore, Sugar’s persistent data storage subsystem for applications. The system was written by an external contractor without OLPC oversight (after I interviewed him and explicitly warned against his hiring!), and is generally a stunning show of incompetence both in software design and implementation. It eventually shut down and rendered inoperable — even after reboot — hundreds of XO laptops in Uruguay a day before the children were supposed to leave for their summer vacation. Left unfixed, it would have soft-bricked all seven thousand deployed machines.
So I decided to check out Ubuntu Mobile, aka Intel's Moblin, on my XO, following these instructions. This stuff is using Hildon, which is the core of Nokia's Maemo environment for their web tablets. Unfortunately, Ubuntu Mobile still has a long way to go to hit Maemo's level of maturity, but at least they've got a head start by sharing open source components. I don't know why Sugar didn't take that route.
My perceptions of Ubuntu Mobile are somewhat skewed by the fact that at the same time I was trying it out, my XO's ctrl and alt keys started sticking, which is a common problem. So, I don't know, I may have to look into returning it. I'd be happy to just buy a new keyboard.