This is a basic breakout board for the FTDI FT232RL USB to serial IC. The pinout of this board matches the FTDI cable to work with official Arduino and cloned 5V Arduino boards. It can also be used for general serial applications. The major difference with this board is that it brings out the DTR pin as opposed to the RTS pin of the FTDI cable. The DTR pin allows an Arduino target to auto-reset when a new Sketch is downloaded. This is a really nice feature to have and allows a sketch to be downloaded without having to hit the reset button. This board will auto reset any Arduino board that has the reset pin brought out to a 6-pin connector.
This board has TX and RX LEDs that allow you to actually see serial traffic on the LEDs to verify if the board is working, but this board requires a miniB cable. The FTDI Cable is well protected against the elements, but is large and cannot be embedded into a project as easily. The FTDI Basic uses DTR to cause a hardware reset where the FTDI cable uses the RTS signal.
This board was designed to decrease the cost of Arduino development and increase ease of use (the auto-reset feature rocks!).
One of the nice features of this board is a jumper on the back of the board that allows the board to be configured to either 3.3V or 5V (both power output and IO level). This board ship default to 5V, but you can cut the default trace and add a solder jumper if you need to switch to 3.3V.
It also has a Xbee socket that can Xbee can be directly plugged onto it.