Unfortunately, you will have problems plugging the ClickPad in, since TI intentionally changed the shape of their hardware.

O.o
If only it were 66666...
And I just noticed DJ is a lobster.

So, based on discussions on IRC over the past few days, these are the current plans for OTARM's firmware (please correct me if I'm wrong):
OS: Most likely a Linux variant, unless we can write a complete OS from scratch quickly enough. Linux is our best bet, since it allows us to use existing libraries and programs, while giving us a stable base for our system. It also runs with minimal resources. Possible distros include Angstrom, Debian, or Arch.
Math software: XCAS is an fairly complete CAS which supports all of the features needed on a calculator. In addition, it has 3 syntax modes (Maple, XCAS, and TI-89), which helps ease the transition from existing platforms to OTARM. The interface and underlying math library (GIAC) are separate, which is good since the current interface has serious user-friendliness issues (for one thing, the English version is partially in French). We will probably be writing our own UI.
Programming language: XCAS is programmable, so that settles the math side of things. For application programming (games, etc.) we will probably write or port a BASIC compiler or interpreter. Either way, it is important that we have a built-in language easier to use than Python or C.
UI concerns: The terminal and root filesystem will be accessible, but hidden from the average user. We don't want to scare new users with the Linux command-line, or with cryptically named folders like /usr, /bin, and /dev.

Have we decided on a GUI toolkit yet? Also, what filesystem type (ext2, ext3, etc.) and GNU utilities (full or Busybox) are we going to be using?
I'll update this post with the latest decisions as time goes on.
It has been pointed out that ext* is not supported by Windows. With this in mind, FAT32 is probably the way to go.

I recommend 1.7 unless you need 1.1. No one needs the new features in 2.x anyway, and the 2.x series is a lot bigger than the 1.x series. Actually, keeping your calculator at 1.1 is not unbearable, unless you make extensive use of the Nspire's BASIC abilities or can't stand the power bug.

Sweet! Thank you

Does the game support exits in the levels yet?

At this point, it is much easier to port games from the Nspire to 68k calcs than it is to port games from 68k to the Nspire.  The 68k series already has just about everything the Nspire has (I can't think of anything it dosen't), so it really just a matter of making some slight syntax changes. (For example, the sprite function is different for both calcs).  Right now, we don't have all of the functions for the Nspire as we do for the 89.  Hopefully in the future we will have all of the functions the 89 has for the Nspire and the job of porting games to the Nspire should be quite easy!

What's the 68k sprite function syntax? I'll change mine to match it, if I can.

Yeah, if we want to port it we are better off porting the individual emulators that make up the package. NES emulation would be nice, though.
Must...get...standard...library...