Here's the linkage:
There's not a great deal to look at around the idler pulley - if you look at the top picture in the article (click to embiggerise) you can see the end of the idler axle on the outside of the swingarm just behind the front mech. That bit of the swingarm is an inverted U-shaped channel that the chain runs inside. I believe that they're changing the idler a bit - it was originally like a jockey wheel that floated on the axle to accommodate gear selection, but there was talk of moving to a full-width roller which was a bit quieter.