What will be in the UT2003 demo?? Well, Unreality snapped up some information from what Mark Rein wrote in the official UT2003 forum. Here is a clip:

1) What build version of UT2003 was being displayed at E3?

The latest one compiled just before E3. This was the first build I saw with a working Ion Cannon which is a ton of fun to use! What we showed on the show floor is essentially what we think the demo will be which consists of two DM maps (Antalus and Curse3), one Double Domination map (Suntemple), one CTF map (Chrome) and one Bombing Run map (Endagra). But, be warned, this could change. I don't believe there are any plans for a single player campaign for the demo.