  The Second International Workshop on Programming Language Approaches to
Concurrency and Communication-cEntric Software (PLACES) was co-located with
ETAPS 2009 in the city of York, England. The workshop took place on Sunday 22nd
March 2009. The workshop focused on the challenges raised by the changing
landscape of computer software. Traditionally, most software was written for a
single computer with one CPU. However applications on the web today are built
using numerous interacting services deployed on across many machines; soon
off-the-shelf CPUs will host thousands of cores, and sensor networks will be
composed from a large number of processing units. Many normal applications will
soon need to make effective use of thousands of computing nodes. At some level
of granularity, computation in such systems will be inherently concurrent and
communication-centred.
  The development of effective programming methodologies for the coming
computing paradigm demands exploration and understanding of a wide variety of
ideas and techniques. This workshop offered a forum where researchers from
different fields could exchange new ideas on one of the central challenges for
programming in the near future, the development of programming methodologies
and infrastructures where concurrency and distribution are the norm rather than
a marginal concern.
