From the kickstarter page for Lords of Gossamer and Shadow
Jason Durall pointed out.
Bridging Doors. While Wardens are limited to Doors that lead to-and-from the Grand Stair, Masters know how to connect two doors in a single Gossamer world together so that they are directly linked, opening from one to another. To do this, the Master must be physically present at one of the doors to be linked (which must be closed) and concentrates on the other door to be linked. This can take a few minutes, less so with a strong mental impression of the other door, and even less with a direct psychic or magic link to the other place. These doors only open from one door within a Gossamer world to another place on the same Gossamer world. They can never bridge worlds.
Bridged doors lack the invulnerability of Doors on the Grand Stair, and they can be accessed and affected by any Warden or Master. These bridged doors are rarely permanent, and the duration will last only so long as the Master desires, usually a matter of days. Making a permanent bridge between two mundane doors takes considerably longer, a process measured in days rather than minutes.
This ability needs some thought, it can be powerful enough to break a lot of scenarios a GM might normally organize.
More later
in the shadow of greatness 
I don’t see how this is much practically different than Trump / Icon? For sure you cannot rely on full-powered LoGaS PCs staying where you put them any more than you can rely on full-powered Amber PCs staying put.
Well, that’s certainly true.
On the other hand, when you Trump to a unique individual, there are social thresholds, favors, perhaps even a conflicting story to introduce. When ‘any old door’ will get you across a world with a couple minutes work, that’s a pretty low threshold.
Is it remarkably different from sorcery and teleportation? Nope. It’s not a game breaker just a slightly different visual/character/story element.
Master of the Grand Stair is a pretty potent power set.
Place trumps, though, are much the same as bridged doors, only even more flexible.
For sure Stairmaster is a potent power!
Yes!
However, I’ve always ‘upgraded the threshold’ of place Trumps. If the artist has no personal/emotional investment in the place depicted, they have a very low chance of making the place Trump work.
I always try to explain that wrinkle to Trump folks in my games before we start. It’s my own interpretation to keep that threshold high and conform to the flavor I see in the Zelazny canon.
I’m not sure anyone else does this, but early in my diceless career, Trump artists making place Trumps of your bedroom at Castle Amber (usually without you knowing) just seemed so so wrong that I reverse engineered a couple things about Trumps.
Still, those pesky sorcerers and their teleport spells!! Ha!
I guess part of the question here is how well do you have to know the other door to make a bridge? My interpretation would be that you have to know the other door pretty well…
I add the extra wrinkle that the doors must be made identical for this purpose. Basically, the rule of Sympathy.
I like that idea. A bit of stage and craft and problem solved without making things too easy.