Though the board will act like a 'standard' Arduino and can be completely driven through the Arduino IDE, it actually runs an Intel Real Time Operating System (RTOS) that Intel has open sourced and is available through their download centre. When the IDE compiles the code it will do the right things and put the right bits on the correct core.
The 101 should support most UNO and Zero shields, though it's a 3.3V board (though Intel say it will tolerate 5V boards). It's powered either through a dedicated 5V socket or through the USB port. It's NOT microUSB but the older chunky USB B socket.
As well as the 2 cores, there's also a 3 axis accelerometer and 3 axis gyroscope so the board can sense it's spacial direction and movement and it also supports Bluetooth Low Energy (BLE) meaning it can do things like become a beacon or talk to your phone.
The tech specs are
|Operating Voltage||3.3V (5V tolerant I/O)|
|Digital I/O Pins||14 (of which 4 provide PWM output)|
|PWM Digital I/O Pins||4|
|Analog Input Pins||6|
|DC Current per I/O Pin||20 mA|
|Flash Memory||196 kB (though on-board 384KB rest for RTOS)|
|SRAM||24 kB (80KB on-board again rest for RTOS)|
|Features||Bluetooth LE, 6-axis accelerometer/gyroscope|
So altogether a nice little Arduino (sorry Genduino) which is pretty fast and pretty compatible.
Pricing varies considerably on-line and it's available from around £16 all the way up to £35, and its available in a variety of kits.