Since 2001, Microsoft has been trying to sell Tablet PCs running the same Windows XP user interface as ordinary computers but they never really took off. What Apple has shown us with the iPhone and iPad is that only a user interface designed from the ground up for touch screens can live up to the expectations we have of tablets: intuitive, fast and fun. But a couple of free software platforms are shaping up to become viable alternatives to Apple’s walled garden. I’m going to look at Android, Ubuntu’s Unity and MeeGo.