This expression (read as "world plus dog") is primarily used on the U.K. information tech news site "The Register" as a synonym for "everyone" or "many, many people". The phrase is apparently an abbreviation for "everyone and his/her dog", expressed in the pithy style of a programmer.

meaning everyone...
more specifically its a technology term used online to refer to products available for both geeks and the general consumer population.
It is often used satirically particularly if the item/product is late to market or been restricted beforehand.