The imx515 is a pretty standard board and Linux support is actively maintained by Freescale. Linux is often an obvious choice for embedded design - Freescale doesn't normally make tablets, but car parts, industrial controllers and moon landings :-) Situations where you don't want a blue screen.
Bodhi has a really nice touch interface. The distro uses enlightenment, which has been developed to run as well on a 30" screen (some cable providers use it for the DVR interface) as well as a cell phone (Openmoko).
I use it on the T91, a touchscreen netvertible, and you just have to choose your applications. Many developers now start to make the buttons a little bigger. And if you use webapps anyway, you can change your browsers' user agent. Most of all, my T91 boots in 27 sec from off to Wifi connection, the OS is lightning fast and uses around 100MB RAM.