As of today, the OpenEZX project has a working touch screen driver. I've been testing this with the Kdrive X11 server of OpenEmbedded, and it seems to work nicely on my A780 after calibrating with ts_calibrate.
This is such a major step forward, since the touch-screen driver requires a functional PCAP2 driver, which in turn comprises working SPI support, as well as some tricky SPI-during-hardirq for interrupt chaining.
If you're interested in giving it a try, there's the the -ezx6 quilt patchset including all this work.
Also, thanks to the work by Michael 'mickey' Lauer, I've managed to set up an OpenEmbedded environment to build a distribution for OpenEZX. You can find the first bunch of packages as well as a root filesystem that you can put on TransFlash on my OpenEZX developer pages.
The availability of a OE based root filesystem, a kernel with keypad, touch-screen, usbnet and framebuffer support actually means that all the [G]UI people can now start to work on making their favourite UI system work on OpenEZX. Given the amount of interest I've seen in this area, I'm confident that I still don't (yet) need to dive into UI development myself but can stay with the more technical low-level stuff.
Speaking of which, I've also hacked a nice tool called gpiotool, using which you can read/write GPIO configuration as well as individual GPIO pins from userspace. If I had written this earlier on, it would have saved a lot of time and hassle. But then, it's always hard pushing yourself to develop code that _just_ aids development and doesn't really add any functionality itself.
Using this tool I'm now investigating the AP/BP interaction (handshake). Let's hope that we can actually use the phone as a phone really soon.