"Last week Ryan 'Icculus' Gordon had confirmed that the Linux
client and server ports of Unreal Tournament 3 were caught up in a
legal issue regarding some middleware used in this latest PC title
from Epic Games. However, what is the middleware that Unreal
Tournament 3 is caught up in? There is a strong possibility that it
deals with the PhysX licensing from Ageia Technologies.
"For those that are not familiar with PhysX, it is a proprietary
physics engine SDK, which can be accelerated by their discrete
Physics Processing Unit..."