The first thing demonstrated was the new content browser, which allows developers to catalog and easily find assets. Utilizing a tag system (hey, just like Joystiq!), developers can quickly pull up assets and even get a fully animated preview of that particular item.
We then moved on to the new Lightmass technology, which allows Epic to fill in dynamic light with ease. No longer do developers have to go in and build an individual light source from scratch, as Lightmass helps to streamline the implementation of light sources. We're no designers, but we're pretty sure this is a good thing.
Finally, we come to what was easily our favorite part of the presentation: MCP. MCP (Master Control Program) allows Epic to analyze multiplayer data from gameplay and provides results on where the most action is. It's impressive to see where players die the most on a map in Gears of War 2, for example, and they even showed us where people were getting revived the most. It's not only cool from a player standpoint, but as a developer, this is juicy info, for sure.
We asked Epic if the new tools in Unreal Engine 3 were available to developers, and they confirmed that some developers did have these additions already. We asked about Rocksteady Studios, who is using Unreal Engine 3 in Batman: Arkham Asylum, and Epic said that these new additions came too late in that company's development cycle for use. But, developers have these tools now, so hopefully they'll be putting them to good use.