CuteUino may sound like a little cute thing. In fact cuteness is not the only thing on it. Frantone came up with a new concept of Arduino. The main idea was to keep Arduino as small as possible and still keep it versatile and expandable. The core board is only 20x20mm which houses chip 16MHz clock, couple LEDs and reset resistor. The PCB is equipped with pinheaders around where expander boards may be stacked.
If you need USB then you can stack the module with FTDI converter chip. It is only a prototype, but idea is plausible enough to be spread.