-multicore support (something like what Krashan described, perhaps even some special threads without pointer based message passing that run in the Q-Box as separate tasks)
-Ambient window plugins to be able to have something like TortoiseCVS/SVN/GIT that adds a small image to icons.
-Accelerated Cairo (perhaps through an OpenGL based OpenVG implementation like Shiva)

once it's ported to G5:
1.-Drivers running on QBox and ABox using some kind of wrapper for drivers (A generic gfx driver, sound driver, network driver... real stuff inside QBox)
2.-64bit version (incompatible with 32bits, supporting various GB of ram)
3.-Ability to launch various boxes (e.g. main 64 bit one running in parallel with a compatible 32bit box)
4.-Communication between boxes
5.-Native port of QBox to X64, running hosted on top of Linux for example before it runs natively.
6.-Port of ABox to X64
7.-Running full PowerPC ABox emulated on top of a PowerPC emulator for X64 (SheepShaver for example).
8.-MorphOS release for X64.