Well, we're through the "OMG will this even work" phase. Aria got FreeType to build on all platforms, so you can load TTF files directly on Windows, Mac, Android, and iOS devices. I set up the accelerometer input on iOS today, so you can call Device::GetAcceleration() and retrieve a Vec3 telling you which way is down. Acceleration is returned relative to the screen orientation, so you don't have to worry about which way the device is rotated. This isn't my proudest screenshot, but it demonstrates that it works. Gravity is pointing in the negative Y direction, relative to the landscape screen orientation.
Multitouch is working on iOS and Android. I am not 100% happy with the way events are handled at this point, but the hard parts are done.
I also got cross-platform threads working. I like the Windows implementation of threads better than POSIX, but our Thread and Mutex classes work the same on everything. I use these internally to optimize routines in the engine, and you are welcome to try them, but be warned! Multithreaded programming is not for the faint of heart, and there's a lot of ways you can hurt yourself! I generally avoid use of mutexes at all, and just try to design my routines so that I send a bunch of data to get processed, then get the results. Otherwise it's just too complicated.
I had an interesting discussion last week with one developer here, and it led to the decision to start using static class functions for creation and loading commands. For example, instead of CreateThread(), you will call Thread::Create() in C++, Lua, and C#. This gives us a uniform API across all three languages, and it resolves the problems that arise from C#'s lack of global functions.
The goal right now is to get all the platform-specific stuff totally resolved and 100% tested so that we can move on and be totally platform-agnostic. That means from now on I can just write code without worrying about whether it's running on Android, Mac, Windows, or whatever. Not much else to say at the moment. Here's a screenshot of the code log to show what we've been working on: