In a large undertaking, the Software Systems Lab, TCD, hosted the ACM SIGPLAN 2009 Conference on Programming Language Design and Implementation on campus in TCD. PLDI is one of the most important and influential Computer Science conferences of the year. Around 280 researchers from academia and industry came to the conference, which had conferences, workshops and events over six days. Dr David Gregg, the local arrangements chair said that he was happy with the conference, and looking forward to a long rest now that it is over.