Unreality tossed up a Chat Log with Epic Games Mark Rein. The time was spent answering a whole bunch of questions regarding UT2003. Here is a clip:

How big is the demo, and how many mirrors are expected to mirror the installer upon release?

I think we have about 200 mirrors lined up thus far! The demo is about 100Mb.

Do you have any ideas for any official/unofficial downloadable/buyable expansion packs for UT2k3 in the near future up to 6 months from now?

We expect to release some extra content but we don't have exact plans and NO we won't be charging for it.