I'm at OOPSLA. An especially interesting talk yesterday was Scale Changes Everything.
Linda Northrop of the Software Engineering Institute spoke about Ultra-Large-Scale (ULS) Systems.
Her concern is that extremely large systems we use throughout life, such as air traffic control and healthcare, are becoming more software-intensive and our techniques for developing, maintaining, deploying, and keeping running such software isn't scaling, so new techniques are needed. If developing a really large system is like creating a big building, and a system of systems is like a city block of interconnected buildings, then a ULS is more like a city--and techniques for building buildings don't scale to cities. Cities defy central planning, must keep running constantly even while parts are taken off-line and repaired or replaced, and problems like fires must be contained and avoided until remedied.
In the panel that followed, The Ultra Challenge: Software Systems Beyond Big, Gregor Kiczales observed that these may be problems with developing applications of any size, but that they become completely unmanagable when the system gets so large. Panelests compared a ULS with a nation's economy, emerging from the behavior of lots of separate components acting somewhat independently.
OOPSLA has a wiki page on Linda's talk.