The Overo Fire COM is the top of the line in the Overo series, at least at the moment. It contains not only built-in Wifi 802.11b/g capabilites but also BlueTooth capabilities on board. This feat of magic is provided by a Marvell W2CBW003 integrated circuit (can be seen on the left side of the board in the picture) which connects to an external WiFi and BlueTooth antenna (not supplied) through a u.fl R.F. connector for each one. Even though the WiFi/BlueTooth radio Integrated Circuit package is only 12-mm x 12-mm in size it packs a great deal of capability. For those in the know - this is the same radio integrated circuit that is on the Beta Overo board and all the software drivers already exist in the operating system installed on the Overo boards. Couple the WiFi and Bluetooth capabilites with the TI OMAP-3530 processor on the Overo Fire COM and you have one very capable device in a very small form-factor! The only thing missing is a video out source on-board to make this a completely self-contained computer system! For video and USB access you will need one of the expansion boards mentioned below or build your own custom interface board.
The Overo Fire COM is the same physical size and electrical connection specifications as the original Overo Earth board so will work with the Summit Expansion board. Speaking of expansion boards Gumstix has come out with a few more in different configurations for the Overo COM series:
Update: As of this moment (June 5, 2009) there is an Interference between the Overo Air COM and Fire COM modules with a component on the Tobi board. In other words you can not use a Overo Air COM or Fire COM with the Tobi board until Gumstix resolves this issue. What does this mean? You can not have 802.11b/g and Bluetooth capabilies on the Tobi board. If those are not a problem you still can use the Overo Earth COM and Water COM on the board without any physical component interference issues. In my opinion (for what it is worth) this really blows! I would want ALL capabilities available (wireless, bluetooth and ethernet) on the board for a full fledged computer in a very very small space, but that is just me.