Last year I declined (or perhaps neglected) to include the 18th World Computer Chess Championship (Software), which was held for the first time. What's the difference between the two events?
The World Computer Chess Championship (WCCC) for the Shannon Trophy will be contested by teams who have no restriction placed on them as to their choice of hardware.
The World Chess Software Championship (WCSC) tournament will be held at the same location, after the WCCC. This will be a uniform platform event using computers loaned by the host organisation. In each game played in this tournament the two computers will be, so far as is possible, identical with respect to their hardware capabilities: number of cores, processor speed, memory size.
This year's WCCC was the first since The Rybka Affair hit top-level computer chess like a sledge hammer. Was the shunning of Rybka a wise move or a witch hunt? The debate continues on forums wherever computer chess is dicussed; see, for example, World Computer Chess Championship (2011) on Chessgames.com.