These microcontroller boards have options for wireless ethernet, wired ethernet, USB, and other goodies for semi-reasonable prices (as far as embedding in projects).
I’ve never seen these Gumstix boards before, but they do look interesting. I typically use Microchip PIC microcontrollers for my projects because they are very small and most importantly, CHEAP. I once bought a BS2 (Basic Stamp 2) which was $50 and I had many dreams of doing cool things with it — that was, until I realized that I’d be having to embed a $50 part into my silly blinking LED project! 😉
Thus, I taught myself how to use the PIC (and therefore, Scenix SX) series of microcontrollers. There was always one thing missing from the PICs and that was some way to connect to the outside world. For some applications, ethernet would be great (for example, to monitor the temp of the kegerator in the basement from my laptop) and other times, USB would be better. However, the PICs have never offered this kind of functionality (easily).
Well, these Gumstix products are getting bookmarked for potential future use. They seem to be based on the Atmel Mega chips, but are pre-mounted on board with a defined interconnect system allowing you to plug various daughterboards in to get extra functionality. They have modules that will accept CompactFlash cards, wireless ethernet PCMCIA cards, and lots of other useful stuff.
I can see all of this being useful for projects above the “blinking LED” projects I like to joke about so much. I can just imagine the home automation, data aquisition, and other intermediate type stuff. I could see using them in my home-made pinball, various robot applications, and all kinds of stuff. They are not as cheap as the PIC, but for those projects which warrant the extra cost to get the ethernet connectivity, it could be worth it.