shape detection

Daring Fireball on The Iconfactory's Linea app update - you can scroll down to the ZipShades video there - as DF quotes:

Simply draw a rough circle, square, rectangle, oval, or polygon and hold at the end. After a configurable delay, ZipShape will activate and transform your rough version into a clean, precise shape. It works with all of Linea’s drawing tools — including the new fill tool.
You don’t have to be perfect — after the shape is generated, there are transform handles you can use to tweak its final position and appearance. No rulers or stencils required!

Gruber calls that "a real standout". Which is fair enough - not many programs support that kind of interaction. But it's not a new idea -
 
that video shows a mid-90s Newton running with the concept.

But you know, it's a lot older than that - here's Ivan Sutherland and Alan Kay showing the way:

That's Sketchpad (a.k.a. Robot Draftsman) all the way back from 1963!

While Steve Jobs was right that HAVING to use a stylus on a phone-sized device was terrible, it's probably not great that it took 5 years into the life of the iPad to introduce a precision stylus, the Apple Pencil.

I'm sure CAD-software has been doing this all along, so I'm not being snarky about this being touted as revolutionary, because it's not, just conceptually cool.