The concept of a Living Campaign World is to essentially have events occurring around or behind the scenes while characters are adventuring through long campaign arcs. If you have the pc's playing in an area for a while throughout the campaign then you can set up something called Campaign Turns. Essentially Campaign turns are a turn the DM takes creating events that happen around or behind the scenes of the actual campaign. For instance let's say the players are adventuring in the Kingdom of Ustalav. While they are going through the modules maybe a huge storm has devastated a local village, or a drought and subsequent food shortage has happened making food more expensive. Or Maybe two guilds are war with each other causing problems with trade and obtaining certain goods. The events can have slight impact on the pc's or not much at all, but they here about throughout their adventures and they may choose to interact with the situation or to just continue along with their adventure. The GM can take a Campaign Turn after each session and a way to keep track of this is to create sort of a character mockup for each type of event or an ongoing rivalry between two guilds so the guilds would be like player characters and could have turns they would take.
Campaign Turn Character possibilities
The King/ Queen / Court
An evil boss
Turn / Action
Roll dice to figure Outcome
41-80 Something good Happens
81-100 Something Terrible Happens