A Survey of Existing Linux Patents

“The Linux world has been all atwitter since Acacia Technologies
Group filed a lawsuit against Red Hat and Novell alleging that
their versions of Linux infringe on three patents. Just how big is
the risk to Linux from patent lawsuits? One indication may come
from a look at current US patent publications related to or
mentioning Linux.

“Computer programs, though often protected by copyright or trade
secrets, cannot be directly patented unless they are used for
something tangible, such as signal processing or hardware