This ABB presentation from December 2013 summarizes the significant changes in each of the parts of IEC61508 which is the safety standard for the design and development of safety systems. Therefore if you would like a quick snapshot of this important document this 42 page slide deck will certainly help.
One common thread through the document is the requirement for increased documentation. This of course should come as no surprise to anyone as there are several other standards already in existence, particularly in Europe that require cradle to grave tracking of system components such as batteries.
The document also provides increased clarity of white and black channel communications, again no surprise considering the number of industrial protocols that do use black channel communications for their safety system implementations.
What I did find interesting were the statistics on control system aging and obsolescence with graphs on that topic on slides 4, 36, and to some extent 37. The graph on page 4 indicates that the average control system is between 11-20 years in service but more interesting is that approximately 25% of systems are 5-10 years service. Is that because they are new, or is this one of the effects of new Commercial Off The Shelf (COTS) based control systems?
The presentation is available at the direct link http://www.lead-central.com/AssetManager/fc469aba-01e7-4ba4-96d0-02dbc762c042/Documents/WhitePapers/ABB-835-WPO_ImplicationsIEC61508Edition.pdf but you may be required to register to get to it.