Feeling guilty for never doing enough round here, I thought I might as well post some pre-news...
On April 1st 3D Realms decided to release the Duke Nukem 3D source code - you can still see their announcement here on their front news page, and despite the date this is no joke!
Already efforts to port the game to various platforms have been started, including our favourite platform, RISC OS. Perhaps the most useful port for us will be the work-in-progress Linux port at icculus.org, because of the Linux compatability we have in the form of GCC and the Unix Porting Project.
Technically there is no reason why the game shouldn't be able to run on RISC OS (It uses an engine a bit more complicated than that in DOOM). Don't hold your breath for too long on this though, as the amount of work needed to port Duke to RISC OS is still unknown.
There are also murmurs of the Blood and Shadow Warrior source being released, as they used the same BUILD engine as Duke 3D; it looks like the next few months should be interesting!
comp.sys.acorn.games thread
3D Realms Duke 3D source forum
Duke 3D for Linux
The BUILD engine porting project