I don't think there is anything fundamentally different between _any_ of the *duino boards, apart from the form-factors. That is one of the interesting aspects about the Arduino ecosystem though: its diversity. IMHO, the Microduino system looks like a collection of awesome little boards that are extremely modular. And yes, that is pretty similar to what the TinyDuino offers.
So what?
The most powerful aspect of the Arduino is not the boards anyway, it's the software platform with the incredible number of libraries that makes it dramatically easier to program the atmega328 and its relatives. In fact, I have never bought an actual Arduino board, but alway rolled my own. But I'm still using the Arduino IDE, even though as an editor is sucks, simply because the libraries make life so much easier.
In case it came out wrong ... I'm not complaining about novelty. I'm merely wondering if I missed something given that so many news outlets are talking about it :)
So what?
The most powerful aspect of the Arduino is not the boards anyway, it's the software platform with the incredible number of libraries that makes it dramatically easier to program the atmega328 and its relatives. In fact, I have never bought an actual Arduino board, but alway rolled my own. But I'm still using the Arduino IDE, even though as an editor is sucks, simply because the libraries make life so much easier.