They're called turtles because, back in the day, they were actual robots that looked like turtles. http://www.ias.uwe.ac.uk/Robots/gwonline/gwonline.html

Yep, they had one of those at my primary school.

Yeah, it's directly inspired from Logo. Logo was great because you were immediately able to program, and immediately see the results on the screen. There wasn't any annoying procedures to do before you could start, no graphics packages to learn. That was my goal here -- to have as few barriers as possible between the person and the programming.

Why turtles? I don't know actually, I'm just following Logo's convention. Some implementations make it a little arrow - I prefer the turtle, especially because kids like it better. Though there isn't really a reason that a turtle should leave a trail, so maybe a slug would make more sense.

Yes. I'm very much in favor of "desired results quickly". For kids, that may be something cool and graphical and/or audible.

For adults, it's often solving a problem at hand.

I think that the ability to gets things done, that one desires, draws many people in. A large initial learning curve before that happens is often a deal breaker.

Once you're engaged, that's the time to keep teaching you more.

Super! I know a kid that has been literally begging me to teach him programming and I have been looking high and low for something like this. The closest I got so far was a logo in javascript: http://www.calormen.com/Logo/