The Hidden Blade Assassin's Creed in Depth

"Superblending" refers to the unintended ability for Ezio to remain hidden (blended) while performing actions that would ordinarily attract attention. Superblending is an incredibly useful exploit that can be used widely throughout the game. Before discussing superblend, let's establish the concepts of "blending grace period" and "standing/non-standing surfaces."

Blending Grace Period
The blending grace period is the short period of time after you've left a group people in which you remain blended with them - even though nobody may be around you. The grace period lasts a few seconds, but it immediately ends if you do anything high profile, such as run or climb. Ezio will sparkle during the grace period, but he will still be blended for a moment after the sparkle has faded. You can confirm the blended status by examining the mini-map. A green border indicates that Ezio is still blended.

Standing/Non-Standing Surfaces
"Standing surfaces" are places where Ezio can stand in a fully upright posture. Streets and rooftops are examples of standing surfaces.

"Non-standing surfaces" are places where Ezio cannot stand in a fully upright posture. For example, the cables that cross between buildings are non-standing surfaces because Ezio crouches as he uses them. Beams, rails, walls, ladders, ledges, horses, and water are all non-standing surfaces.

Superblending
To initiate superblending, you need to first blend with a group of people, and then transition to a non-standing surface during the blending grace period. Since high profile actions (such as running up a wall) immediately end the blending grace period, there are only a few ways in which superblending can be initiated:

1:18 Get on a ladder by walking up to it
3:22 Hang over any ledge (e.g., on a roof or bridge, or at the water's edge) by pressing drop
4:26 Climb up a rail (or similar) by holding your movement towards the rail
5:40 Mount a horse by approaching it or pressing free hand

There may be additional ways to initiate superblending that are not shown here.

Once you initiate superblending, you are invisible to opponents as long as you remain on non-standing surfaces. That means you can climb, jump, drop, grasp, swim, gallop, crouch, etc. Avoid aggressive actions, such as punching, throwing a knife, or trampling others with the horse, as such actions may break the superblend.

Part of the challenge of superblending is figuring out how to get to your ultimate destination from where you can initiate superblending. In this regard, horses are strategic because they are mobile. You can move a horse next to a group of people, initiate the superblend, and then ride away to your final destination. Similarly, you can hire courtesans to follow you to a ladder.

Two special types of standing surfaces are exceptions that allow you to maintain superblend status: treasure boats and gondolas. You can even loot treasure boats and travel in gondolas while remaining superblended.

6:42 Superblending is also a easy way to hide from Seekers, as they are not programmed to look for you on most non-standing surfaces.

The contextual camera is available while you are superblended, which offers a nice opportunity to change the camera angle. I like to use it during air assassinations.

If you think superblending is cool, just wait til you see hyperblending:
http://www.thehiddenblade.com/hyperblend-exploit