Very, very different things.

The BBB and the Raspberry Pi are designed to be relatively high-power (both computational, and power draw from DC) devices running a true multiuser OS.

This thing is more akin to an Arduino Micro or a Teensy - a low-power controller that could run a very long time on a tiny battery, no OS to speak of, just a single loop of essentially real-time code.

I just made a hardware clock for my PC (7-segment LED display mounted in a CD-ROM bay slot). I used an Arduino Micro to drive the display.

I may build a dedicated media server at home. A RasPi or BBB would be perfect.

I'm thinking to launch a stratospheric balloon. I need something to hold together and drive a GPS sensor, temperature sensor, VGA camera, SD card, and radio transmitter. Total weight and power consumption are severely limited. An Arduino or Teensy would be great.

Do a wall-mount big LCD screen at the office, showing the vital stats of our website in real time, for all to see? A RasPi or BBB.

Or you could go even more bare-metal and do everything with an AVR that costs $1 and a few components that you recover from the last floor sweep, like this:

http://florin.myip.org/blog/how-make-halloween-creepy-blinki...

See the differences? Horses for courses.

I agree about the arduino and batteries, but this board is a bit different.

It uses external memory which takes more power. It uses javascript which could take much more power. And the wifi also might not be low power. So it's not clear yet how low power it is.

Yes, but if you're using javascript you're probably not aiming for long battery life or high performance per dollar. Tessel is not like an ATmega 8; it's like a BBB.

Looks like the JavaScript bindings for Tessel are better. Comparing the demo for blinking an LED:

  var b = require('bonescript');
  var state = 0;

  b.pinMode("USR3", 'out');
  setInterval(function() {
    state = state ? 0 : 1;
    b.digitalWrite("USR3", state);
  }, 100);

vs

  var tessel = require('tessel')
  tessel.led(1).blink()

If they can give human-friendly names to stuff like "USR3" and "P9_40" and "P9_36" out of the box, then I'd say they've added some value.

But that's a library issue, not a hardware issue. It shouldn't be difficult to write a wrapper for bonescript that turns the first example into the second example.

And what happens when you need to specify a pin mode on the Tessel? If you don't have at least tri-state support (which isn't compatible with human-friendly abstractions like "blink"), you're going to burn out a lot of sensors.

Most modern microcontrollers have anywhere from 3 to 5 possible pin states, and I don't think it's possible to safely wrap these up in a nice, human-friendly function like "blink".

For example, on a lot of ARMs, you have:

In, no pull

In, pulled up

In, pulled down

Out, up

Out, down

and on AVRs, you have

In, no pull

In, pulled up

Out, up

Out, down

You necessarily have to have ugly secondary functions like "pinMode".

Also: peripheral muxing, interrupts in input mode, connecting a timer as PWM output to a pin (which is basically what blink is probably doing). In input mode it might also have schmitt triggering.

Where's the blink getting the timer from? What happens if I update the main PLLs? I'll refrain from making assumptions however until I can see their driver libraries. I'm hopeful, but having played around with the 1830 it's not a simple chip.

You forgot the best part: not having to deal with javascript.

I don't see a price yet for this one. I like the pi (and the beaglebone) because they've already got the network hardware, but the gpio isn't as robust as on the arduino (3.3v vs 5v, very low current capacity on the pi, and no analog io).

I can't say I particularly want the javascript, but if they've got wifi and arduino compatible gpio for ~ $25, then I can find a use for it.

BeagleBone Black has a huge number of gpio pins, it's one of BeagleBoard's major selling points over RasPi at this point. I'm fairly certain the BeagleBone Black has more gpio pins than the Arduino.

BeagleBone Black also has a real-time module (effectively, a limited microcontroller on the same die as the CPU), which I expect could make for some sweet libraries.

Does the Pi have WiFi, though? Mine doesn't, but perhaps I don't have the latest model.

No it doesn't, but since it has USB ports you can augment it with a USB wifi module. A word of warning though. If you're thinking of buying one of these, make sure to check that it has good Linux support.