Crytek had just one Linux box at the show, which was running Ubuntu and showing the CRYENGINE running on Linux. As I wrote in the CRYENGINE article earlier, "Not many at GDC were excited about Linux support particularly. On the first day of the expo, only about six people had commented/recognized it was CRYENGINE on Linux."
At Intel's booth I found no Linux systems at all, but all of their demos seemed to be Windows-based.
At the AMD booth was one Linux box. The AMD Linux box was a slow A8 system showing that GPU PerfStudio can be run on Windows and connect to a Linux system for OpenGL debugging. GPU PerfStudio itself doesn't run on Linux for now but they were just showing that the AMD software can be used from a Windows system for debugging Linux OpenGL games/applications. Ubuntu was in use on the AMD A8 APU system.
LunarG happened to be at the Game Developer's Conference but their booth wasn't manned the entire time and featured just a laptop for showing off their work on OpenGL tracing/re-playing.
The most concentrated showing of non-Linux Android at GDC 2014 were the Steam Boxes running the Debian-based SteamOS.
At booths like Unity, Epic Games, Occulus, Qualcomm, and elsewhere, I didn't see any pure Linux (non-Android) works on display. Of course, I was there for just a day and a half, so I might have missed another one or two Linux systems, but Linux game support was far from being heavily advertised at GDC 2014 or a popular topic. When asking random game companies and other stakeholders about Linux, many of them responded they were mostly focused on Windows games at this time, the Linux gaming market is small, or that they simply didn't have anything to show off that couldn't be done better under Windows. Stay tuned though for some more exciting GDC Linux exclusives in the coming days, aside from the articles already posted today covering Ubisoft on Linux, CRYENGINE Linux details, etc.